U.S. patent application number 13/024953 was filed with the patent office on 2016-07-07 for photoelectric conversion element, photoelectric conversion apparatus and solid-state imaging apparatus.
This patent application is currently assigned to SONY CORPORATION. The applicant listed for this patent is Osamu Enoki, Masaki Murata, Masanori Oka. Invention is credited to Osamu Enoki, Masaki Murata, Masanori Oka.
Application Number | 20160195573 13/024953 |
Document ID | / |
Family ID | 44148985 |
Filed Date | 2016-07-07 |
United States Patent
Application |
20160195573 |
Kind Code |
A9 |
Murata; Masaki ; et
al. |
July 7, 2016 |
PHOTOELECTRIC CONVERSION ELEMENT, PHOTOELECTRIC CONVERSION
APPARATUS AND SOLID-STATE IMAGING APPARATUS
Abstract
A method of detecting a change in current is provided which
includes irradiating light on at least one photoelectric conversion
material layer, and detecting an increased change in current
generated in the photoelectric conversion material layer. A
photoelectric conversion apparatus is also provided and includes a
photoelectric conversion element including a photoelectric
conversion material layer, and a current detection circuit
electrically connected to the photoelectric conversion element. In
the photoelectric conversion apparatus, the current detection
circuit detects an increased change in current generated in the
photoelectric conversion material layer.
Inventors: |
Murata; Masaki; (Tokyo,
JP) ; Oka; Masanori; (Kanagawa, JP) ; Enoki;
Osamu; (Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Murata; Masaki
Oka; Masanori
Enoki; Osamu |
Tokyo
Kanagawa
Kanagawa |
|
JP
JP
JP |
|
|
Assignee: |
SONY CORPORATION
Tokyo
JP
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20120143544 A1 |
June 7, 2012 |
|
|
Family ID: |
44148985 |
Appl. No.: |
13/024953 |
Filed: |
February 10, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12510392 |
Jul 28, 2009 |
8212201 |
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13024953 |
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Current U.S.
Class: |
250/208.1 ;
250/206; 257/40; 257/431; 257/443; 257/E31.11; 257/E51.012;
324/76.11; 324/96; 702/64 |
Current CPC
Class: |
H01L 51/0078 20130101;
H01L 51/4206 20130101; H01L 27/307 20130101; H01L 51/0092 20130101;
H01L 2031/0344 20130101; G01R 19/0092 20130101; Y02E 10/549
20130101; H01L 51/0081 20130101; H01L 31/032 20130101; H01L 31/09
20130101; H01L 31/035218 20130101; H01L 51/0072 20130101; H01L
27/14665 20130101; H01L 27/14609 20130101 |
International
Class: |
G06F 19/00 20110101
G06F019/00; H01L 31/02 20060101 H01L031/02; G01R 19/00 20060101
G01R019/00; H01L 51/00 20060101 H01L051/00; H01L 27/146 20060101
H01L027/146; H01L 31/032 20060101 H01L031/032; H01L 31/0352
20060101 H01L031/0352; H01L 51/42 20060101 H01L051/42; H01L 27/30
20060101 H01L027/30 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 17, 2010 |
JP |
P2010-032179 |
Jan 14, 2011 |
JP |
P2011-005620 |
Claims
1. A method of detecting a change in current comprising:
irradiating light on at least one photoelectric conversion material
layer; and detecting an increased change in current generated in
the photoelectric conversion material layer.
2. The method of detecting a change in current according to claim
1, further comprising detecting a current I.sub.inc in a current
increasing period according to the following formula (1):
I.sub.inc=C.sub.1*I.sub.o(P)*[1-e.sup.(-t/.tau.(P))]+C.sub.2 (1)
wherein .tau.(P) represents a time constant of the changes in the
current in the current increasing period from a first time to a
second time, wherein t represents an elapsed time from the first
time to the second time, wherein I.sub.0(P) represents a current
generated in the photoelectric conversion material layer when light
at an intensity P is irradiated on the photoelectric conversion
material layer when t=.infin., and wherein C.sub.1 and C.sub.2
represent constants.
3. The method of detecting a change in current according to claim
2, wherein the second time occurs at or before a time of transition
from the current increasing period to a current decreasing
period.
4. The method of detecting a change in current according to claim
2, further comprising calculating the integral current value by
integrating formula (I) from t=0 to about t=100 milliseconds.
5. The method of detecting a change in current according to claim
1, wherein the photoelectric conversion material layer is formed
between a first electrode and a second electrode, the method
further comprising: detecting changes in the current generated in
the photoelectric conversion material layer from a first time
corresponding with (a) an initiation of irradiation of light on the
photoelectric conversion material layer, or (b) an initiation of
voltage application to the first electrode and the second
electrode, to a second time occurring after the first time.
6. The method of detecting a change in current according to claim
5, wherein the changes in current in the photoelectric conversion
material layer from the first time to the second time correspond to
changes in charge current in a capacitor defined by the first
electrode, the second electrode, and the photoelectric conversion
material layer.
7. The method of detecting a change in current according to claim
6, further comprising detecting a time constant of the changes in
the current in a current increasing period from the first time to
the second time as .tau.(P), wherein .tau.(P) is a function of a
light intensity P per unit time of the irradiation of the light on
the photoelectric conversion material layer.
8. The method of detecting a change in current according to claim
1, wherein the photoelectric conversion material layer includes at
least one organic semiconducting material selected from the group
consisting of organic colorants represented by quinacridone and the
derivatives thereof, colorants of an early transition metal ion
chelated by an organic material represented by Alq3
[tris(8-quinolinolato)aluminum(III)], and organic metal colorants
having a complex formed between a transition metal ion and an
organic material represented by phthalocyanine zinc (II).
9. The method of detecting a change in current according to claim
1, wherein the photoelectric conversion material layer includes at
least one material selected from the group consisting of organic
metal compounds, organic semiconductor fine particles, metal oxide
semiconductors, inorganic semiconductor fine particles, core-shell
materials, and organic/inorganic hybrid compounds.
10. The method of detecting a change in current according to claim
1, wherein the photoelectric conversion material layer has a
carrier mobility of less than or equal to 10 cm.sup.2/V*second.
11. A photoelectric conversion element comprising: at least one
photoelectric conversion material layer configured to enable a
detection of an increased change in current generated in said
photoelectric conversion material layer.
12. The photoelectric conversion apparatus according to claim 11,
further comprising a first electrode and a second electrode, the
photoelectric conversion material layer being disposed between the
first electrode and the second electrode.
13. The photoelectric conversion apparatus according to claim 12,
wherein the first electrode is comprised of a transparent
conductive material and is formed on a transparent substrate,
wherein the photoelectric conversion material layer is formed on
the first electrode, and wherein the second electrode is formed on
the photoelectric conversion material layer.
14. The photoelectric conversion apparatus according to claim 12,
wherein the first electrode is formed on a substrate, wherein the
photoelectric conversion material layer is formed on the first
electrode, and wherein the second electrode is comprised of a
transparent conductive material and is formed on the photoelectric
conversion material layer.
15. The photoelectric conversion apparatus according to claim 12,
wherein the first electrode and the second electrodes are formed on
a substrate, and wherein the photoelectric conversion material
layer is formed on the substrate in a region between the first
electrode and the second electrode.
16. The photoelectric conversion element according to claim 11,
wherein the photoelectric conversion material layer is configured
to enable a detection of current I.sub.inc in a current increasing
period according to the following formula (1):
I.sub.inc=C.sub.1*I.sub.o(P)*[1-e.sup.(-t/.tau.(P))]+C.sub.2 (1)
wherein .tau.(P) represents a time constant of the changes in the
current in the current increasing period from a first time to a
second time, wherein t represents an elapsed time from the first
time to the second time, wherein I.sub.0(P) represents a current
generated in the photoelectric conversion material layer when light
at an intensity P is irradiated on the photoelectric conversion
material when t=.infin., and wherein C.sub.1 and C.sub.2 represent
constants.
17. The photoelectric conversion element according to claim 16,
wherein the second time occurs at or before a time of transition
from the current increasing period to a current decreasing
period.
18. The photoelectric conversion element according to claim 16,
further comprising calculating the integral current value by
integrating formula (I) from t=0 to about t=100 milliseconds.
19. The photoelectric conversion element according to claim 11,
wherein the photoelectric conversion material layer is configured
to enable a detection of the current generated in the photoelectric
conversion material layer from a first time corresponding with (a)
an initiation of irradiation of light on the photoelectric
conversion material layer, or (b) an initiation of voltage
application to the photoelectric conversion material layer, to a
second time occurring after the first time.
20. The photoelectric conversion element according to claim 19,
wherein the photoelectric conversion material layer is configured
to enable a detection of a time constant of the changes in the
current in a current increasing period from the first time to the
second time as .tau.(P), and wherein .tau.(P) is a function of a
light intensity P per unit time of the irradiation of the light on
the photoelectric conversion material layer.
21. The photoelectric conversion element according to claim 11,
wherein the photoelectric conversion material layer includes at
least one organic semiconducting material selected from the group
consisting of organic colorants represented by quinacridone and the
derivatives thereof, colorants of an early transition metal ion
chelated by an organic material represented by Alq3
[tris(8-quinolinolato)aluminum(III)], and organic metal colorants
having a complex formed between a transition metal ion and an
organic material represented by phthalocyanine zinc (II).
22. The photoelectric conversion element according to claim 11,
wherein the photoelectric conversion material layer includes at
least one material selected from the group consisting of organic
metal compounds, organic semiconductor fine particles, metal oxide
semiconductors, inorganic semiconductor fine particles, core-shell
materials, and organic/inorganic hybrid compounds.
23. The photoelectric conversion element according to claim 11,
wherein the photoelectric conversion material layer has a carrier
mobility less than or equal to 10 cm.sup.2/V*second.
24. A photoelectric conversion apparatus comprising: a
photoelectric conversion element including at least one
photoelectric conversion material layer; and a current detection
circuit electrically connected to the photoelectric conversion
element, wherein the current detection circuit detects an increased
change in current generated in the photoelectric conversion
material layer.
25. A solid state imaging apparatus comprising: an imaging region
including at least one photoelectric conversion element having at
least one photoelectric conversion material layer; and a current
detection circuit electrically connected to at least one of the
photoelectric conversion elements, wherein the current detection
circuit detects an increased change in current generated in the
photoelectric conversion material layer.
26. The solid state imaging apparatus according to claim 25,
wherein the imaging region includes a plurality of photoelectric
conversion elements arranged in an array, and wherein each of the
photoelectric conversion elements includes a first electrode, a
second electrode, and a photoelectric conversion material layer
disposed between the first electrode and the second electrode.
27. The solid state imaging apparatus according to claim 26,
further comprising a plurality of current detection circuits,
wherein each of the photoelectric conversion elements is connected
to a different one of the plurality of current detection
circuits.
28. The solid state imaging apparatus according to claim 26,
wherein the array is a two-dimensional array including rows and
columns, and wherein the current detection circuit is formed for a
row or a column of photoelectric conversion elements.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] The present application claims priority to Japanese Patent
Application JP 2010-032179 filed on Feb. 17, 2010 and Japanese
Patent Application JP 2011-005620 filed on Jan. 14, 2011, the
entire contents of which is hereby incorporated by reference.
BACKGROUND
[0002] The present disclosure relates to a photoelectric conversion
element, a photoelectric conversion apparatus having the
photoelectric conversion element, and a solid-state imaging
apparatus having the incorporated photoelectric conversion
apparatus.
[0003] Photoelectric conversion elements such as image sensors
normally have a structure in which a photoelectric conversion unit
is held between two electrodes. The output from a photoelectric
conversion element (e.g., electric current), which is not dependent
on time, is detected as steady output (steady current). This is
because semiconductor materials for example of silicon (Si)
accumulate carriers instantaneously and give steady current under
the electric field at the intensity generally used.
[0004] Image sensors having a photoelectric conversion unit made of
an organic semiconductor material are known, for example as
disclosed in Japanese Patent Application Laid-open No. 2006-100797
(hereinafter, referred to as Patent Document 1). Such an image
sensor has an organic photoelectric conversion layer held between
at least two electrodes, and the organic photoelectric conversion
layer contains a quinacridone or quinazoline derivative.
SUMMARY
[0005] In the technology disclosed in Patent Document 1 above, a
signal is read out by using a common color read-out circuit (see
paragraph number [0135]). Thus, in the image sensor disclosed in
Patent Document 1, the signal outputted and read out from the
photoelectric conversion element is considered to be part of an
output signal in the steady state that is not dependent on time.
However, detection of the part of an output signal in the steady
state causes a problem that the sensitivity and the S/N ratio are
lower.
[0006] Thus, there is a need for a new photoelectric conversion
element having a photoelectric conversion material layer with high
sensitivity and high S/N ratio, a photoelectric conversion
apparatus having such a photoelectric conversion element
incorporated, and a solid-state imaging apparatus having such a
photoelectric conversion apparatus incorporated.
[0007] Photoelectric conversion elements produced by using a
Si-based semiconductor material for its photoelectric conversion
material layer generally have very low electrical resistance. In
contrast, for example, thin films of metal oxide or organic
material are generally higher in resistance and lower in carrier
mobility than Si-based semiconductor materials, independently of
their crystallinity. Specifically, thin films of metal oxide
material or organic material have low carrier mobility, high
resistance, and additionally many defect levels, and it is very
difficult to inject carriers to an amount that fills the capacity
of the thin layer instantaneously even under very high-intensity
electric field. Therefore, such a film demands a certain period of
time for stabilization of the electric potential distribution in
the thin film including formation of an interfacial electrical
double layer. Thus, although electric charges accumulate in the
photoelectric conversion material layer, when light is irradiated
to the photoelectric conversion material layer while voltage is
applied to the photoelectric conversion material layer, it is
possible to observe the transient charge/discharge current
generated in the photoelectric conversion material layer because
the time constant .tau. of the photoelectric conversion material
layer is sufficiently large (in the order of several microseconds
to several milliseconds).
[0008] In an embodiment, a method of detecting a change in current
includes irradiating light on at least one photoelectric conversion
material layer. The method also includes detecting an increased
change in current generated in the photoelectric conversion
material layer. In an embodiment, the method includes detecting a
current I.sub.inc in a current increasing period according to the
following formula (I):
I.sub.inc=C.sub.1*I.sub.o(P)*[1-e.sup.(-t/.tau.(P))]+C.sub.2
(1)
[0009] In formula (1), .tau.(P) represents a time constant of the
changes in the current in the current increasing period from a
first time to a second time, t represents an elapsed time from the
first time to the second time, I.sub.0(P) represents a current
generated in the photoelectric conversion material layer when light
at an intensity P is irradiated on the photoelectric conversion
material layer when t=.infin., and C.sub.1 and C.sub.2 represent
constants. In an embodiment, the second time occurs at or before a
time of transition from the current increasing period to a current
decreasing period. In an embodiment, the method further includes
calculating the integral current value by integrating formula (1)
from t=0 to about t=100 milliseconds. In an embodiment, the
photoelectric conversion material layer is formed between a first
electrode and a second electrode, and the method further includes:
detecting changes in the current generated in the photoelectric
conversion material layer from a first time corresponding with (a)
an initiation of irradiation of light on the photoelectric
conversion material layer, or (b) an initiation of voltage
application to the first electrode and the second electrode, to a
second time occurring after the first time. In an embodiment, the
changes in current in the photoelectric conversion material layer
from the first time to the second time correspond to changes in
charge current in a capacitor defined by the first electrode, the
second electrode, and the photoelectric conversion material layer.
In an embodiment, the method further includes detecting a time
constant of the changes in the current in a current increasing
period from the first time to the second time as .tau.(P), wherein
.tau.(P) is a function of a light intensity P per unit time of the
irradiation of the light on the photoelectric conversion material
layer. In an embodiment, the photoelectric conversion material
layer includes at least one organic semiconducting material
selected from the group consisting of organic colorants represented
by quinacridone and the derivatives thereof, colorants of an early
transition metal ion chelated by an organic material represented by
Alq3 [tris(8-quinolinolato)aluminum(III)], and organic metal
colorants having a complex formed between a transition metal ion
and an organic material represented by phthalocyanine zinc (II). In
an embodiment, the photoelectric conversion material includes at
least one material selected from the group consisting of organic
metal compounds, organic semiconductor fine particles, metal oxide
semiconductors, inorganic semiconductor fine particles, core-shell
materials, and organic/inorganic hybrid compounds. In an
embodiment, the photoelectric conversion material is formed as a
photoelectric conversion material layer having a carrier mobility
of less than or equal to 10 cm.sup.2/V*second.
[0010] In another embodiment, a photoelectric conversion element
includes at least one photoelectric conversion material layer
configured to enable a detection of an increased change in current
generated in said photoelectric conversion material layer. In an
embodiment, the photoelectric conversion element further includes a
first electrode and a second electrode, the photoelectric
conversion material layer being disposed between the first
electrode and the second electrode. In an embodiment, the first
electrode is comprised of a transparent conductive material and is
formed on a transparent substrate, the photoelectric conversion
material layer is formed on the first electrode, and the second
electrode is formed on the photoelectric conversion material layer.
In an embodiment, the first electrode is formed on a substrate, the
photoelectric conversion material layer is formed on the first
electrode, and the second electrode is comprised of a transparent
conductive material and is formed on the photoelectric conversion
material layer. In an embodiment, the first electrode and the
second electrodes are formed on a substrate, and the photoelectric
conversion material layer is formed on the substrate in a region
between the first electrode and the second electrode. In an
embodiment, the photoelectric conversion material layer is
configured to enable a detection of current I.sub.inc in a current
increasing period according to the following formula (1):
I.sub.inc=C.sub.1*I.sub.o(P)*[1-e.sup.(-t/.tau.(P))]+C.sub.2
(1)
[0011] In formula (1), .tau.(P) represents a time constant of the
changes in the current in the current increasing period from a
first time to a second time, t represents an elapsed time from the
first time to the second time, I.sub.0(P) represents a current
generated in the photoelectric conversion material layer when light
at an intensity P is irradiated on the photoelectric conversion
material when t=.infin., and C.sub.1 and C.sub.2 represent
constants. In an embodiment, the second time occurs at or before a
time of transition from the current increasing period to a current
decreasing period. In an embodiment, the photoelectric conversion
element further includes calculating the integral current value by
integrating formula (1) from t=0 to about t=100 milliseconds. In an
embodiment, the photoelectric conversion material layer is
configured to enable a detection of the current generated in the
photoelectric conversion material layer from a first time
corresponding with (a) an initiation of irradiation of light on the
photoelectric conversion material layer, or (b) an initiation of
voltage application to the photoelectric conversion material layer,
to a second time occurring after the first time. In an embodiment,
the photoelectric conversion material layer is configured to enable
a detection of a time constant of the changes in the current in a
current increasing period from the first time to the second time as
.tau.(P), and .tau.(P) is a function of a light intensity P per
unit time of the irradiation of the light on the photoelectric
conversion material layer. In an embodiment, the photoelectric
conversion material layer includes at least one organic
semiconducting material selected from the group consisting of
organic colorants represented by quinacridone and the derivatives
thereof, colorants of an early transition metal ion chelated by an
organic material represented by Alq3
[tris(8-quinolinolato)aluminum(III)], and organic metal colorants
having a complex formed between a transition metal ion and an
organic material represented by phthalocyanine zinc (II). In an
embodiment, the photoelectric conversion material layer includes at
least one material selected from the group consisting of organic
metal compounds, organic semiconductor fine particles, metal oxide
semiconductors, inorganic semiconductor fine particles, core-shell
materials, and organic/inorganic hybrid compounds. In an
embodiment, the photoelectric conversion material layer has a
carrier mobility less than or equal to 10 cm.sup.2/V*second.
[0012] In another embodiment, a photoelectric conversion apparatus
includes a photoelectric conversion element including at least one
photoelectric conversion material layer, and a current detection
circuit electrically connected to the photoelectric conversion
element. In this embodiment, the current detection circuit detects
an increased change in current generated in the photoelectric
conversion material layer.
[0013] In another embodiment, a solid state imaging apparatus
includes an imaging region including at least one photoelectric
conversion element having at least one photoelectric conversion
material layer, and a current detection circuit electrically
connected to at least one of the photoelectric conversion elements.
In this embodiment, the current detection circuit detects an
increased change in current generated in the photoelectric
conversion material layer. In an embodiment, the imaging region
includes a plurality of photoelectric conversion elements arranged
in an array, and each of the photoelectric conversion elements
includes a first electrode, a second electrode, and a photoelectric
conversion material layer disposed between the first electrode and
the second electrode. In an embodiment, the solid state imaging
apparatus further includes a plurality of current detection
circuits, wherein each of the photoelectric conversion elements is
connected to a different one of the plurality of current detection
circuits. In an embodiment, the array is a two-dimensional array
including rows and columns, and the current detection circuit is
formed for a row or a column of photoelectric conversion
elements.
[0014] In the photoelectric conversion element according to an
embodiment, the photoelectric conversion element constituting the
photoelectric conversion apparatus according to an embodiment, and
the photoelectric conversion element constituting the solid-state
imaging apparatus according to an embodiment (hereinafter, these
are collectively referred to as the "photoelectric conversion
element and others according to an embodiment"), when light at a
particular light intensity is irradiated to the photoelectric
conversion material layer while voltage is applied between the
first and second electrodes (i.e., while bias voltage is applied
between the first and second electrodes), the electric current
generated in the photoelectric conversion material layer increases
with elapse of the irradiation time from initiation of irradiation.
It is thus possible to provide a high-sensitivity and high-S/N
ratio photoelectric conversion element or the like by detecting
such electric current. In other words, it is possible to determine
the intensity of the light received based on the charge current. In
particular, it is possible to detect transient response within a
very short period of about 5 milliseconds or less even when light
at very strong light intensity, which may saturate known
photodiodes, is irradiated, and thus, it is possible to detect the
light at light intensity that may saturate known photodiodes. It is
thus possible to expand the dynamic range when it is used as a
solid-state imaging apparatus. As for the current-time response and
the dependence on light intensity when light is irradiated to the
photoelectric conversion material layer, the electric current area
of charge current (time integral value of current) is dependent on
light intensity.
[0015] Additional features and advantages are described herein, and
will be apparent from the following Detailed Description and the
figures.
BRIEF DESCRIPTION OF THE FIGURES
[0016] FIG. 1 is a schematic cross-sectional view illustrating a
photoelectric conversion element of Example 1 in a two-terminal
electronic device structure;
[0017] FIG. 2 is a graph showing a relationship between the charge
current value and the light intensity in the photoelectric
conversion element of Example 1;
[0018] FIG. 3 is a graph showing a relationship between the light
intensity P of the light irradiated to a photoelectric conversion
material layer per unit time (unit: .mu.W/cm.sup.2) and a value
[.alpha.(P)] having a unit of [-1/.tau.(P)] in Example 1;
[0019] FIG. 4 is a graph showing a relationship between the charge
current value and the light intensity in the photoelectric
conversion element of Example 2;
[0020] FIG. 5 is a graph showing a relationship between the light
intensity P of the light irradiated to a photoelectric conversion
material layer per unit time (unit: .mu.W/cm.sup.2) and a value
[.alpha.(P)] having a unit of [-1/.tau.(P)] in Example 2;
[0021] FIGS. 6A and 6B are partial schematic cross-sectional views
respectively illustrating photoelectric conversion elements in a
two-terminal electronic device structure of Examples 3 and 4;
[0022] FIGS. 7A and 7B are partial schematic cross-sectional views
respectively illustrating photoelectric conversion elements in a
three-terminal electronic device structure of Examples 5 and 6;
[0023] FIGS. 8A and 8B are partial schematic cross-sectional views
respectively illustrating photoelectric conversion elements in a
three-terminal electronic device structure of Examples 7 and 8;
[0024] FIG. 9 is a schematic diagram showing a solid-state imaging
apparatus of Example 9; and
[0025] FIG. 10 is a circuit diagram showing an example of a current
detection circuit.
DETAILED DESCRIPTION
[0026] Hereinafter, an embodiment of will be described with
reference to the drawings. The various numerical values and
materials indicated in the embodiments are merely examples. The
following items will be described in this order:
[0027] 1. General description of the photoelectric conversion
element, photoelectric conversion apparatus, and solid-state
imaging apparatus according to an embodiment,
[0028] 2. Example 1 (photoelectric conversion element and
photoelectric conversion apparatus according to an embodiment and
photoelectric conversion element in first configuration),
[0029] 3. Example 2 (a variation of Example 1),
[0030] 4. Example 3 (a variation of Example 1, photoelectric
conversion element in second configuration),
[0031] 5. Example 4 (another variation of Example 1, photoelectric
conversion element in third configuration),
[0032] 6. Example 5 (another variation of Example 1, three-terminal
electronic device structure),
[0033] 7. Example 6 (another variation of Example 1, three-terminal
electronic device structure),
[0034] 8. Example 7 (another variation of Example 1, three-terminal
electronic device structure),
[0035] 9. Example 8 (another variation of Example 1, three-terminal
electronic device structure), and
[0036] 10. Example 9 (solid-state imaging apparatus according to an
embodiment) and others.
[0037] [General Description of Photoelectric Conversion Element,
Photoelectric Conversion Apparatus, and Solid-State Imaging
Apparatus According to an Embodiment]
[0038] In the photoelectric conversion element and others according
to an embodiment, when a time constant of the change in electric
current increasing with elapse of the irradiation time from its
initiation is designated as .tau.(P), .tau.(P) may be expressed by
a function of the light intensity P per unit time of the light
irradiated to the photoelectric conversion material layer.
Specifically, for example, a value [.alpha.(P)] having a unit of
[-1/.tau.(P)] can be expressed by a linear function of the light
intensity P per unit time of the light irradiated to the
photoelectric conversion material layer. In the photoelectric
conversion apparatus or the solid-state imaging apparatus according
to an embodiment, it is possible to cause the current detection
circuit to calculate .tau.(P). Specifically, it is possible to
obtain the light intensity P per unit time of the light irradiated
to the photoelectric conversion material layer, by calculating
.tau.(P) in the current detection circuit.
[0039] In such a case, the current I.sub.inc generated in the
photoelectric conversion material layer of the photoelectric
conversion element and others according to an embodiment can be
expressed, when the time elapsed from initiation of irradiation or
application of voltage to the first and second electrodes is
designated as t, by:
[0040] Iinc=C1I0(P) [1-exp(-t/.tau.(P))]+C2(1) and, in the
photoelectric conversion apparatus or the solid-state imaging
apparatus according to an embodiment, it is possible to cause the
current detection circuit to calculate I.sub.inc, additionally. In
the formula above, I.sub.0(P) is the electric current generated in
the photoelectric conversion material layer when it is assumed that
light at a certain light intensity P is irradiated to the
photoelectric conversion material layer when t=.infin., and C.sub.1
and C.sub.2 are constants. C.sub.1 is a positive value.
[0041] In the photoelectric conversion apparatus or the solid-state
imaging apparatus according to an embodiment, in the above case,
the current detection circuit may additionally be configured to
calculate the integral current value obtained by integrating the
Formula (I) from t=0 up to t=100 milliseconds. Also in the
photoelectric conversion element according to an embodiment, the
integral current value (including physical quantities calculated
based on the integral current value) obtained by integrating the
Formula (I) from t=0 up to t=100 milliseconds may be caused to show
dependence on light intensity.
[0042] In the photoelectric conversion apparatus, the solid-state
imaging apparatus, or the photoelectric conversion element
according to an embodiment, the increase of the current in the
photoelectric conversion material layer with elapse of irradiation
time may correspond to the change of the charge current in the
capacitor, when it is assumed that the first electrode, the
photoelectric conversion material layer, and the second electrode
constitute a capacitor.
[0043] In addition, in the photoelectric conversion apparatuses,
the solid-state imaging apparatuses, or the photoelectric
conversion elements according to an embodiment, the photoelectric
conversion material layer is desirably made of an organic material.
In such a case, the photoelectric conversion material layer more
desirably has a carrier mobility of 10 cm.sup.2/Vsecond or
less.
[0044] In the photoelectric conversion elements and others
according to an embodiment, the first electrode made of a
transparent conductive material may be formed on a transparent
substrate, the photoelectric conversion material layer on the first
electrode, and the second electrode on the photoelectric conversion
material layer. Such a configuration will be referred to, for
convenience, as the "photoelectric conversion element in the first
configuration". Alternatively, the first electrode may be formed on
a substrate, the photoelectric conversion material layer on the
first electrode, and the second electrode made of a transparent
conductive material on the photoelectric conversion material layer.
Such a configuration will be referred to, for convenience, as the
"photoelectric conversion element in the second configuration".
Alternatively, the first and second electrodes may be formed on a
substrate, and the photoelectric conversion material layer on a
region of the substrate from the first electrode to the second
electrode. Such a configuration will be referred to, for
convenience, as the "photoelectric conversion element in the third
configuration".
[0045] In the photoelectric conversion elements and others
according to an embodiment in the preferred embodiments and
configurations including those described above, the photoelectric
conversion material layer may be in an amorphous state or in a
crystalline state. Moreover, the method for detecting changes in
current can be applied to one photoelectric conversion material
layer or multiple photoelectric conversion material layers. In the
case where there are two or more photoelectric conversion material
layers, the method includes separately detecting the increased
changes in current generated in each of the photoelectric
conversion material layers.
[0046] Examples of the organic materials constituting the
photoelectric conversion material layer include organic
semiconductor materials, more specifically, organic colorants
represented by quinacridone and the derivatives thereof, colorants
of an early transition metal (metal on the left side of periodic
table) ion chelated by an organic material represented by Alq3
[tris(8-quinolinolato)aluminum(III)], and organic metal colorants
having a complex formed between a transition metal ion and an
organic material represented by phthalocyanine zinc (II), and
dinaphtho-thieno-thiophene (DNTT) represented by the following
structural formula:
##STR00001##
[0047] Alternatively, examples of the materials constituting the
photoelectric conversion material layer for use include organic
metal compounds, organic semiconductor fine particles, metal oxide
semiconductors, inorganic semiconductor fine particles, core-shell
materials, and organic/inorganic hybrid compounds. Specific
examples of the organic metal compounds include the above-described
colorants of an early transition metal ions chelated by an organic
material, and the organic metal colorants having a complex formed
between a transition metal ion and an organic material.
[0048] Specific examples of the organic semiconductor fine
particles include aggregates of the organic colorants described
above represented by quinacridone and the derivatives thereof,
aggregates of the colorants of an early transition metal ion
chelated by an organic material, aggregates of organic metal
colorants having a complex formed between a transition metal ion
and an organic material, Prussian blue and the derivatives having
metal ion crosslinked with cyano groups, and the mixtures of these
aggregates.
[0049] Specific examples of the metal oxide semiconductors and the
inorganic semiconductor fine particles include ITO, IGZO, ZnO, IZO,
IrO.sub.2, TiO.sub.2, SnO.sub.2, SiO.sub.x, metal chalcogen
semiconductors containing chalcogens [for example, sulfur (S),
selenium (Se) or tellurium (Te)] (specifically, CdS, CdSe, ZnS,
CdSe/CdS, CdSe/ZnS, PbSe), ZnO, CdTe, GaAs, and Si.
[0050] A range of an average particle diameter R.sub.AVE of the
fine particles is not particularly limited, but is
5.0.times.10.sup.-10 m.ltoreq.R.sub.AVE.ltoreq.1.0.times.10.sup.-6
m, desirably 5.0.times.10.sup.-10
m.ltoreq.R.sub.AVE.ltoreq.1.times.10.sup.-8 m, and more desirably
5.0.times.10.sup.-10 m.ltoreq.R.sub.AVE.ltoreq.1.0.times.10.sup.-7
m, and the fine particles are desirably highly dispersible in water
or organic solvent. The absorption band of the fine particles is
desirably located in the visible light range of 380 nm to 800 nm,
the near-infrared range of 800 nm to 1500 nm, or the visible light
region of 380 nm to 800 nm and the near-infrared range of 800 nm to
1500 nm. A shape of the fine particle may be spherical, but is not
limited thereto, and the shape may be, for example, triangular,
tetrahedral, cubic, rectangular, conical, cylindrical (rod),
triangular prism, fibrous, pill-like fiber, or the like. When the
fine particle has a non-spherical shape, the average particle
diameter R.sub.AVE of the particle can be calculated, by
determining the average diameter of a spherical particle having the
volume identical with that of the fine particle. The average
particle diameter R.sub.AVE of the fine particles can be obtained
by measuring the particle diameter of the fine particles, for
example, observed with transmission electron microscope (TEM).
[0051] Specific examples of the core-shell materials, i.e.,
combinations of (core material and shell material), include organic
materials such as (polystyrene and polyaniline) and metal materials
such as (hardly ionizable metal material and easily ionizable metal
material).
[0052] Specific examples of the organic-inorganic hybrid compounds
include Prussian blue and the derivatives thereof having metal ions
crosslinked with cyano groups, and also coordination polymers, a
generic term indicating those having metal ions completely
crosslinked with bipyridine and those having metal ions crosslinked
with a polyvalent ionic acid, represented by oxalic acid and
rubeanic acid.
[0053] Examples of the methods of forming the photoelectric
conversion material layer, which depend on the materials used,
include coating methods, physical vapor deposition (PVD) methods,
and various chemical vapor deposition (CVD) methods including
MOCVD. Specific examples of the coating methods include spin
coating method; immersion method; casting method; various printing
methods such as screen printing, inkjet printing, offset printing,
and gravure printing; stamping method; spraying method; and other
various coating methods including air doctor coater method, blade
coater method, rod coater method, knife coater method, squeeze
coater method, reverse roll coater method, transfer roll coater
method, gravure coater method, kiss coater method, cast coater
method, spray coater method, slit orifice coater method, and
calendering-coater method. Examples of the solvents used in the
coating method include nonpolar or less polar organic solvents such
as toluene, chloroform, hexane, and ethanol. Examples of the PVD
methods include various vacuum deposition methods such as electron
beam heating method, resistance heating method, and flash vapor
deposition; plasma vapor deposition method; various sputtering
methods such as bipolar sputtering method, direct current
sputtering method, direct current magnetron sputtering method,
high-frequency sputtering method, magnetron sputtering method, ion
beam sputtering method, and bias sputtering method; and various ion
plating methods such as DC (direct current) method, RF method,
multi-cathode method, activation reaction method, electric field
vapor deposition method, high-frequency ion plating method, and
reactive ion plating method.
[0054] The thickness of the photoelectric conversion material layer
is not particularly limited, but is, for example,
1.times.10.sup.-10 m to 5.times.10.sup.-7 m.
[0055] The voltage (bias voltage) applied between the first
electrode and the second electrode is, for example, 1 millivolt to
15 volts, although it depends on the materials constituting the
photoelectric conversion layer. The electric current generated in
the photoelectric conversion material layer when light at a certain
light intensity P is irradiated to the photoelectric conversion
material layer increases with elapse of the irradiation time, and
the irradiation time of the light at a certain light intensity P
is, for example, 1.times.10.sup.-12 second to 1.times.10.sup.-1
second, although it depends on the material constituting the
photoelectric conversion material layer. Although the electric
current generated in the photoelectric conversion material layer
increases with elapse of the irradiation time, the increase or the
increase rate depends on the materials constituting the
photoelectric conversion material layer and cannot be determined
unambiguously. Thus, it may be determined after various tests.
[0056] The time constant .tau.(P) is expressed by a function of the
light intensity P per unit time of the light irradiated to the
photoelectric conversion material layer, but the function of light
intensity P can be obtained after conducting various tests, and the
function of light intensity P may be stored, for example, in the
current detection circuit. Similarly, the relationship between the
electric current I.sub.inc and the light intensity P per unit time
of the light irradiated to the photoelectric conversion material
layer can be obtained after various tests, and the relationship may
also be stored, for example, in the current detection circuit. In a
preferred configuration, the current detection circuit determines
the integral current value for example by integrating Formula (1),
but may determine the light intensity P based on the integral
current value containing only the first member of Formula (1)
(including physical quantities calculated based on the integral
current value), or based on integral current value containing the
first and second members of Formula (1) (including physical
quantities calculated based on the integral current value), and the
relationship between the integral current value (including physical
quantities calculated based on the integral current value) and the
light intensity P may also be stored, for example, in the current
detection circuit. Alternatively, the light intensity P can be
determined, based on the time t and the electric current I.sub.inc
according to Formula (1).
[0057] The current detection circuit may be a current detection
circuit in any known configuration or structure, if it can
calculate .tau.(P) or determine I.sub.inc or light intensity P.
Other constituents of the solid-state imaging apparatus may also be
known constituents.
[0058] The first and second electrodes are separated from each
other, for example as the second electrode is formed above the
first electrode (photoelectric conversion element in the first or
second configuration) or as the first and second electrodes are
formed as they face each other on a substrate (photoelectric
conversion element in the third configuration).
[0059] A structure of the photoelectric conversion element and
others according to an embodiment is not limited to a two-terminal
electronic device structure having the first and second electrodes,
and may be a three-terminal electronic device structure
additionally having a control electrode, in which the flow of
electric current can be modulated by application of voltage to the
control electrode. Specific examples of the three-terminal
electronic device structures include the configurations and
structures identical with those of so-called bottom gate/bottom
contact-type, bottom gate/top contact-type, top gate/bottom
contact-type, and top gate/top contact-type field effect
transistors (FETs).
[0060] More specifically, the photoelectric conversion element or
the like according to an embodiment in the bottom gate/bottom
contact-type three-terminal electronic device structure has
[0061] (a) a control electrode formed on a support (equivalent to
gate electrode),
[0062] (b) an insulation layer formed on the control electrode and
the support (equivalent to gate insulation layer),
[0063] (c) first and second electrodes formed on the insulation
layer (equivalent to source and drain electrodes), and
[0064] (d) a photoelectric conversion material layer formed on the
insulation layer between the first and second electrodes
(equivalent to channel forming region).
[0065] The photoelectric conversion element or the like according
to an embodiment in the bottom gate/top contact-type three-terminal
electronic device structure has
[0066] (a) a control electrode formed on a support (equivalent to
gate electrode),
[0067] (b) an insulation layer formed on the control electrode and
the support (equivalent to gate insulation layer),
[0068] (c) a photoelectric conversion material layer (equivalent to
channel forming region) and the peripheral region of the
photoelectric conversion material layer formed on the insulation
layer, and
[0069] (d) first and second electrodes formed on the peripheral
region of the photoelectric conversion material layer (equivalent
to source and drain electrodes).
[0070] Alternatively, the photoelectric conversion element or the
like according to an embodiment in the top gate/bottom contact-type
three-terminal electronic device structure has
[0071] (a) first and second electrodes formed on a support
(equivalent to source and drain electrodes),
[0072] (b) a photoelectric conversion material layer formed on the
support between the first and second electrodes (equivalent to
channel forming region),
[0073] (c) an insulation layer formed on the first and second
electrodes and the photoelectric conversion material layer
(equivalent to gate insulation layer), and
[0074] (d) a control electrode formed on the insulation layer
(equivalent to gate electrode).
[0075] Alternatively, the photoelectric conversion element or the
like according to an embodiment in the top gate/top contact-type
three-terminal electronic device structure includes
[0076] (a) a photoelectric conversion material layer (equivalent to
channel forming region) and the peripheral region of the
photoelectric conversion material layer formed on a substrate,
[0077] (b) first and second electrodes formed on the peripheral
region of the photoelectric conversion material layer (equivalent
to source and drain electrodes),
[0078] (c) an insulation layer formed on the first and second
electrodes and the photoelectric conversion material layer
(equivalent to gate insulation layer), and
[0079] (d) a control electrode formed on the insulation layer
(equivalent to gate electrode).
[0080] Examples of the transparent conductive materials
constituting the first or second electrode include indium tin
oxides (including ITO, Sn-doped In.sub.2O.sub.3, crystalline ITO,
and amorphous ITO), IFO (F-doped In.sub.2O.sub.3), tin oxide
(SnO.sub.2), ATO (Sb-doped SnO.sub.2), FTO (F-doped SnO.sub.2),
zinc oxides (including Al-doped ZnO, B-doped ZnO, and Ga-doped
ZnO), indium oxide-zinc oxide (IZO), titanium oxide (TiO.sub.2),
spinel oxides, and oxides having the YbFe.sub.2O.sub.4 structure.
The first or second electrode made of one of these materials
normally has high work function and functions as an anode
electrode. Examples of the methods of forming the transparent
electrode include PVD methods such as vacuum deposition method,
reactive vapor deposition method, various sputtering method,
electron beam vapor deposition method, and ion plating method;
various CVD methods such as pyrosol method, organic metal
compound-pyrolyzing method, spraying method, dipping method, and
MOCVD method; and electroless and electrolytic plating methods,
although the method depends on the materials constituting the
transparent electrode.
[0081] The conductive material constituting the first or second
electrode, which is used when transparency is not required, is
desirably a conductive material having high work function (for
example, .phi.=4.5 eV to 5.5 eV), if the first electrode or second
electrode is used as the anode electrode (positive electrode),
i.e., as an electrode for withdrawing positive holes, and specific
examples thereof include gold (Au), silver (Ag), chromium (Cr),
nickel (Ni), palladium (Pd), platinum (Pt), iron (Fe), iridium
(Ir), germanium (Ge), osmium (Os), rhenium (Re), and tellurium
(Te). On the other hand, when the first or second electrode is used
as the cathode electrode (negative electrode), i.e., as an
electrode for withdrawing electrons, it is desirably a conductive
material having low work function (for example, .phi.=3.5 eV to 4.5
eV), and specific examples thereof include alkali metals (such as
Li, Na, and K) and the fluorides or oxides thereof, alkali-earth
metals (such as Mg and Ca) and the fluorides or oxides thereof,
aluminum (Al), zinc (Zn), tin (Sn), thallium (Tl), sodium/potassium
alloys, aluminum/lithium alloys, magnesium/silver alloys, rare
earth metals such as indium and ytterbium, and the alloys
thereof.
[0082] Alternatively, examples of the materials constituting the
first, second, or control electrode include metals such as platinum
(Pt), gold (Au), palladium (Pd), chromium (Cr), nickel (Ni),
aluminum (Al), silver (Ag), tantalum (Ta), tungsten (W), copper
(Cu), titanium (Ti), indium (In), tin (Sn), iron (Fe), cobalt (Co),
and molybdenum (Mo); alloys containing these metal elements,
conductive particles of these metals, conductive particles of the
alloys containing these metals, polysilicons containing impurities,
conductive substances such as carbonic materials, oxide
semiconductors, carbon nanotubes, and graphenes, and the electrode
may have a laminated structure having the layers containing these
elements. Other examples of the materials constituting the first,
second, or control electrode include organic materials (conductive
polymers) such as poly
(3,4-ethylenedioxythiophene)/polystyrenesulfonic acid
[pEDOT/PSS].
[0083] Examples of the methods of forming the first, second or
control electrode include various PVD methods described above;
various CVD methods including MOCVD method; various coating methods
described above; lift-off method; sol-gel method; electrodeposition
method; shadow mask method; plating methods such as electrolytic
plating method, electroless plating method, or the combination
thereof; and spraying methods, and the combinations as needed with
patterning technology, although the method depends on the materials
constituting the electrode.
[0084] Examples of the substrate or the support (hereinafter,
referred to collectively as substrate or the like) include organic
polymers (flexible polymeric materials in the shape of plastic
film, sheet, plate or the like) such as polymethyl methacrylate
(PMMA), polyvinylalcohol (PVA), polyvinylphenol (PVP), polyether
sulfone (PES), polyimide, polycarbonate (PC), polyethylene
terephthalate (PET), and polyethylene naphthalate (PEN), as well as
mica. Such a substrate or the like of the flexible polymeric
material, if used, allows incorporation or integration thereof in
electronic devices for example having a curved surface shape. Other
examples of the substrates or the like include various glass
substrates, various glass substrates with surface insulation film
formed thereon, quartz substrates, quartz substrates having surface
insulation film formed thereon, silicon substrates having surface
insulation film formed thereon, and metal substrates made of
various alloys and various metals such as stainless steel. Examples
of the insulation films include silicon oxide-based materials (for
example, SiO.sub.x and spin-on glass (SOG)); silicon nitride
(SiN.sub.y); silicon oxide nitride (SiON); aluminum oxide
(Al.sub.2O.sub.3); metal oxides, and metal salts. Alternatively, a
conductive substrate having one of these insulation films formed on
the surface (substrate of a metal such as gold or aluminum or a
substrate of highly oriented graphite) may also be used. The
surface of the substrate or the like is desirably smooth, but may
have a roughness that does not exert adverse effects on the
properties of the photoelectric conversion material layer. It may
be possible to improve the adhesiveness between the first, second
or control electrode with the substrate or the like by forming a
silanol derivative by silane coupling method, a thin film of a
thiol derivative, carboxylic acid derivative, phosphoric acid
derivative or other derivatives by SAM method or the like, or a
thin film of an insulating metal salt or metal complex, for
example, by CVD method on the surface of the substrate or the like.
The transparent substrate is a substrate made of a material that
does not excessively absorb the light entering the photoelectric
conversion material layer through the substrate.
[0085] The electrode or the photoelectric conversion material layer
may be coated with a coating layer, as needed. Examples of the
materials for the coating layer include silicon oxide-based
materials; silicon nitride (SiN.sub.y); inorganic insulating
materials such as highly dielectric insulation films of a metal
oxide such as aluminum oxide (Al.sub.2O.sub.3); polymethyl
methacrylate (PMMA); polyvinylphenol (PVP); polyvinylalcohol (PVA);
polyimides; polycarbonates (PC); polyethylene terephthalate (PET);
polystyrene; silanol derivatives (silane-coupling agents) such as
N-2 (aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS),
3-mercaptopropyltrimethoxysilane (MPTMS), and
octadecyltrichlorosilane (OTS); and organic insulating materials
(organic polymers) such as straight-chain hydrocarbons having
functional groups that can bind to the control electrode at one
terminal such as octadecanethiol and dodecyl isocyanate. These
compounds can be used in combination. Examples of the silicon
oxide-based materials include silicon oxide (SiO.sub.x), BPSG, PSG,
BSG, AsSG, PbSG, silicon oxide nitride (SiON), SOG (spin-on glass),
and low-dielectric constant materials (such as polyarylether,
cycloperfluorocarbon polymers, and benzocyclobutene, cyclic
fluoroplastics, polytetrafluoroethylene, arylether fluoride,
polyimide fluoride, amorphous carbon, and organic SOG).
[0086] Examples of the materials for the insulation layer include
inorganic insulating materials including silicon oxide-based
materials, silicon nitride (SiN.sub.y), and highly dielectric
insulation films of a metal oxide such as aluminum oxide
(Al.sub.2O.sub.3); and also polymethyl methacrylate (PMMA);
polyvinylphenol (PVP); polyvinylalcohol (PVA); polyimides;
polycarbonate (PC); polyethylene terephthalate (PET); polystyrene;
silanol derivatives (silane-coupling agents) such as N-2
(aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS),
3-mercaptopropyltrimethoxysilane (MPTMS), and
octadecyltrichlorosilane (OTS); and organic insulating materials
(organic polymers) such as straight-chain hydrocarbons having
functional groups that can bind to the control electrode at one
terminal such as octadecanethiol and dodecyl isocyanate. These
compounds may be used in combination. Examples of the silicon
oxide-based materials include silicon oxide (SiO.sub.x), BPSG, PSG,
BSG, AsSG, PbSG, silicon oxide nitride (SiON), SOG (spin-on glass),
and low dielectric materials (such as polyarylether,
cycloperfluorocarbon polymers, and benzocyclobutene, cyclic
fluoroplastics, polytetrafluoroethylene, arylether fluoride,
polyimide fluoride, amorphous carbon, and organic SOG).
[0087] Examples of the methods of forming the insulation layer
include various PVD method described above; various CVD methods;
spin coating method; various coating methods described above;
sol-gel method; electrodeposition method; shadow mask method; and
spraying method. Alternatively, the insulation layer can be formed
by oxidation or nitridation of the surface of the control electrode
or by forming an oxide or nitride layer on the surface of the
control electrode. The methods of oxidizing the surface of the
control electrode include, for example, an oxidation method using
O.sub.2 plasma and an anodic oxidation method, although the
suitable method depends on the materials constituting the control
electrode. The method of nitriding the surface of the control
electrode is, for example, a nitriding method using N.sub.2 plasma,
although the suitable method depends on the materials constituting
the control electrode. Alternatively, for example in the case of Au
electrode, it is possible to form an insulation layer on the
surface of the control electrode, by coating the control electrode
surface with an insulating molecule having functional groups
chemically binding to the control electrode, such as a
straight-chain hydrocarbon having a terminal modified with a
mercapto group, by a method such as immersion method in a self
organization manner. Yet alternatively, it is possible to form the
insulation layer by modifying the surface of the control electrode
with a silanol derivative (silane-coupling agent).
[0088] It is possible, with the photoelectric conversion apparatus,
or the photoelectric conversion element or the like according to an
embodiment, to provide optical sensors and image sensors in
addition to imaging apparatus (solid-state imaging apparatus) such
as televisions and cameras.
Example 1
[0089] Example 1 relates to a photoelectric conversion apparatus
and a photoelectric conversion element according to an embodiment
and, more specifically, the photoelectric conversion element of
Example 1 is a photoelectric conversion element in the first
configuration. As shown in the schematic cross-sectional view of
FIG. 1, a photoelectric conversion element 11 of Example 1 has
[0090] (A) a first electrode 21 and a second electrode 22 formed
separately, and
[0091] (B) a photoelectric conversion material layer 30 formed
between the first electrode 21 and the second electrode 22. The
photoelectric conversion apparatus of Example 1 has the
photoelectric conversion element 11 and additionally a current
detection circuit 40.
[0092] In the photoelectric conversion element 11 of Example 1, the
photoelectric conversion apparatus of Example 1, or the
photoelectric conversion element 11 constituting the solid-state
imaging apparatus described below, the electric current generated
in the photoelectric conversion material layer 30, when light at a
certain light intensity P is irradiated to the photoelectric
conversion material layer 30 while voltage is applied between the
first electrode 21 and the second electrode 22, increases with
elapse of the irradiation time from initiation of irradiation. In
addition, in the photoelectric conversion apparatus of Example 1 or
the solid-state imaging apparatus described below, the current
detection circuit 40 detects the electric current (or change in
electric current). The current detection circuit 40 is connected to
the first electrode 21 and the second electrode 22 and applies
voltage between the first electrode 21 and the second electrode
22.
[0093] In the photoelectric conversion element 11 of Example 1, the
first electrode 21 made of a transparent conductive material is
formed on a transparent substrate 20, the photoelectric conversion
material layer 30 on the first electrode 21, and the second
electrode 22 on the photoelectric conversion material layer 30.
Light then enters the photoelectric conversion material layer 30
through the substrate 20 and the first electrode 21.
[0094] The substrate 20 is a glass plate having a thickness of 0.7
mm; the first electrode 21 is made of a transparent conductive
material (specifically, ITO having a thickness of 120 nm); the
second electrode 22 is made of an aluminum (Al) material having a
thickness 100 nm; and the photoelectric conversion material layer
30 is made of an organic material, specifically, an organic
semiconductor material (more specifically, a quinacridone layer
having a thickness of 50 nm). The photoelectric conversion material
layer 30 has a carrier mobility of 10 cm.sup.2/Vsecond or less (for
example, about 10.sup.-3 cm.sup.2/Vsecond to 10.sup.-6
cm.sup.2/Vsecond).
[0095] The photoelectric conversion element 11 of Example 1 can be
prepared by the following method: First, the first electrode 21, an
ITO layer having a thickness of 120 nm, is formed on the substrate
20 by lithography using a photomask. Then, protrusions 31 of an
insulating material are formed on the substrate 20 and the first
electrode 21, and a photoelectric conversion material layer 30 of
quinacridone having a thickness of 50 nm is formed over the first
electrode 21 and the protrusion 31 by vacuum deposition method. A
second electrode 22 of aluminum having a thickness of 100 nm is
then formed over the photoelectric conversion material layer 30 and
the substrate 20 by a PVD method of using a metal mask. The
protrusion 31 is formed as it surrounds the region of the substrate
20 where the photoelectric conversion material layer 30 is to be
formed.
[0096] Light at a wavelength of 565 nm was irradiated at a certain
light intensity P to the photoelectric conversion material layer 30
in the photoelectric conversion element 11 of Example 1 thus
obtained, through the transparent substrate 20 and the first
electrode 21. A voltage of 15 volts is applied to the first
electrode 21, while the second electrode 22 is grounded. The
electric current generated then in the photoelectric conversion
material layer 30 increased with elapse of the irradiation time.
The increase of the electric current generated in the photoelectric
conversion material layer 30 with elapse of irradiation time in the
photoelectric conversion element 11 corresponds to the change of
the charge current in the capacitor, when it is assumed that the
first electrode 21, the photoelectric conversion material layer 30,
and the second electrode 22 form a capacitor. In other words,
charge current was generated in the photoelectric conversion
element 11. When the time constant of the change in electric
current increasing with elapse of the irradiation time from
initiation of irradiation is designated as .tau.(P), .tau.(P) is
expressed by a function of the light intensity P of the light
irradiated to the photoelectric conversion material layer 30 per
unit time. The current detection circuit 40 calculates .tau.(P).
When the elapsed time from initiation of irradiation or from
initiation of voltage application to the first electrode 21 and the
second electrode 22 is designated by t, the electric current
I.sub.inc generated in the photoelectric conversion material layer
30 is expressed by:
I.sub.inc=C.sub.1*I.sub.0(P)*[1-exp(-t/.tau.(P))]+C.sub.2 (1)
[0097] Here, when the photoelectric conversion element 11 or the
photoelectric conversion apparatus has means for controlling the
light irradiated to the photoelectric conversion material layer 30
(for example, shutter), t may be set as the elapsed time from
initiation of irradiation, while, when it has no means for
controlling the light irradiated to the photoelectric conversion
material layer 30, t may be set as the elapsed time from initiation
of voltage application to the first electrode 21 and the second
electrode 22 (initiation of application of bias voltage).
"I.sub.0(P)" is the electric current generated in the photoelectric
conversion material layer 30, when it is postulated that light at a
certain light intensity P is irradiated to the photoelectric
conversion material layer 30 when t=.infin., and C.sub.1 and
C.sub.2 are constants. C.sub.1 is a positive value, and, for
example, C.sub.1=1. In the photoelectric conversion apparatus or
the solid-state imaging apparatus described below, I.sub.inc is
additionally determined by the current detection circuit 40.
Specifically, the charge current is detected by a known current
detection circuit 40 connected to the first electrode 21 and the
second electrode 22. In the photoelectric conversion apparatus, the
current detection circuit 40 may determine the integral current
value (in Example 1, electric charge quantity, a physical quantity
calculated based on integral current value), by integrating the
Formula (I), for example, from t=0 up to t=100 milliseconds. In the
photoelectric conversion element 11, the integral current value (in
Example 1, electric charge quantity, a physical quantity calculated
based on integral current value) obtained by integrating the
Formula (1), for example, from t=0 up to t=100 milliseconds shows
dependence on light intensity.
[0098] The relationship between the charge current value (electric
current I.sub.inc) and the light intensity thus obtained is shown
in FIG. 2. The abscissa in FIG. 2 represents the elapsed time t
described above (unit: arbitrary), and the ordinate in FIG. 2
represents the electric current I.sub.inc described above. The
relationship between the light intensity P of the light irradiated
to the photoelectric conversion material layer 30 per unit time
(unit: .mu.W/cm.sup.2) and the value [.alpha.(P)] having a unit of
[-1/.tau.(P)] obtained is shown in FIG. 3. The abscissa in FIG. 3
represents the value of the light intensity P, while the ordinate
represents the value [.alpha.(P)] having a unit of [-1/.tau.(P)],
i.e., inverse of time constant .tau.(P). The curve "A" in FIG. 2
shows the results obtained when the light intensity P of the light
having a wavelength of 565 nm per unit time is 10 .mu.W/cm.sup.2 as
a voltage of 15 volt is applied to the first electrode 21 and the
second electrode 22 is grounded; the curve "B" shows the results
when it is 5 .mu.W/cm.sup.2; the curve "C" shows the results when
it is 1 .mu.W/cm.sup.2; the curve "D" shows the results when it is
0.5 .mu.W/cm.sup.2; the curve "E" shows the results when it is 0.1
.mu.W/cm.sup.2; and the curve "F" shows the results when the light
is not irradiated.
[0099] FIG. 2 shows that the charge current value is dependent on
light intensity P. Alternatively, FIG. 3 shows that the value
[.alpha.(P)] having a unit of [-1/.tau.(P)] can be expressed by a
linear function of the light intensity P of the light irradiated to
the photoelectric conversion material layer 30 per unit time,
specifically by:
.alpha.(P)=0.5644P+0.4605
[0100] where R.sup.2=0.9743.
[0101] However, the linear function is merely an example.
[0102] Since the function of electric current I.sub.inc, the
coefficient of Formula (1), and the time constant .tau.(P),
respectively with a variable of light intensity P, are dependent on
the configuration, structure, and constituent materials of the
photoelectric conversion element 11, these functions should be
determined by various tests, every time when the configuration,
structure, or constituent materials of the photoelectric conversion
element change, and these functions only needs to be stored in the
current detection circuit 40 (or dedicated circuit or the like) or
a table thereof only needs to be stored in the current detection
circuit 40 (or dedicated circuit or the like).
[0103] In the photoelectric conversion element 11 of Example 1, the
electric current generated in the photoelectric conversion material
layer 30 increases with elapse of the irradiation time, when light
at a certain light intensity is irradiated to the photoelectric
conversion material layer 30 as bias voltage is applied between the
first electrode 21 and the second electrode 22. It is thus possible
to obtain a photoelectric conversion element with high sensitivity
and high S/N ratio, by detecting the electric current.
Example 2
[0104] Example 2 is a variation of Example 1. Regarding the
photoelectric conversion apparatus and the photoelectric conversion
element of Example 2, the photoelectric conversion material layer
30 was constituted of the DNTT having a thickness of 10 nm. In
order to produce the photoelectric conversion element 11 of Example
2, by vacuum deposition, the photoelectric conversion material
layer 30 constituted of the DNTT having a thickness of 100 nm is
formed on the protrusions 31 so as to extend from the first
electrode 21. Except for the above-mentioned points, the
configuration and the structure of the photoelectric conversion
apparatus and the photoelectric conversion element of Example 2 are
similar to those in the photoelectric conversion apparatus and the
photoelectric conversion element of described in Example 1, and no
detailed description thereof is provided.
[0105] The photoelectric conversion material layer 30 of the
photoelectric conversion element 11 of Example 2 thus obtained is
irradiated with light having a constant light intensity P of a
wavelength of 440 nm via the transparent substrate 20 and the first
electrode 21. It should be noted that -5 volts is applied to the
first electrode 21, and the second electrode 22 is in a ground
state. At this time, the photoelectric conversion apparatus and the
photoelectric conversion element of Example 2 shows the same
behavior as that of the photoelectric conversion apparatus and the
photoelectric conversion element of Example 1. The relationship
between the charge current value (current I.sub.inc) and the light
intensity is shown in FIG. 4. The abscissa and the ordinate in FIG.
4 are the same those in FIG. 2. The relationship between the light
intensity P of the light irradiated to the photoelectric conversion
material layer 30 per unit time (unit: .mu.W/cm.sup.2) and the
value [.alpha.(P)] having a unit of [-1/.tau.(P)] is shown in FIG.
5. The abscissa and the ordinate in FIG. 5 are the same those in
FIG. 3. The curve "A" in FIG. 4 shows the results obtained when the
light intensity P of the light having a wavelength of 440 nm per
unit time is 2 .mu.W/cm.sup.2 as -5 volts is applied to the first
electrode 21 and the second electrode 22 is grounded; the curve "B"
shows the results when it is 5 .mu.W/cm.sup.2; and the curve "C"
shows the results when it is 15 .mu.W/cm.sup.2.
[0106] FIG. 4 shows that the charge current value is dependent on
light intensity P. Alternatively, FIG. 4 shows that the value
[.alpha.(P)] having a unit of [-1/.tau.(P)] can be expressed by a
linear function of the light intensity P of the light irradiated to
the photoelectric conversion material layer 30 per unit time,
specifically by:
.alpha.(P)=0.7655P+2.9027
[0107] where R.sup.2=0.998.
Example 3
[0108] Example 3 is a variation of Example 1 or Example 2. A
photoelectric conversion element 12 of Example 3 is a photoelectric
conversion element in the second configuration. As shown in the
partial schematic cross-sectional view of FIG. 6A, a first
electrode 21A is formed on a substrate 20A; a photoelectric
conversion material layer 30 is formed on the first electrode 21A;
and a second electrode 22A of a transparent conductive material is
formed on the photoelectric conversion material layer 30. Light
enters the photoelectric conversion material layer 30 through the
second electrode 22A. Specifically, the substrate 20A is made, for
example, of a silicon semiconductor substrate, the first electrode
21A is made of aluminum, and the second electrode 22A is made of
ITO. Except for these points above, the configuration and the
structure of the photoelectric conversion element 12 or the
photoelectric conversion apparatus of Example 3 are similar to
those in the photoelectric conversion element 11 or the
photoelectric conversion apparatus of Example 1 or Example 2, and
no detailed description thereof is provided.
Example 4
[0109] Example 4 is also a variation of Example 1 or Example 2. A
photoelectric conversion element 13 of Example 4 is a photoelectric
conversion element in the third configuration. As shown in the
partial schematic cross-sectional view of FIG. 6B, a first
electrode 21B and a second electrode 22B are formed on a substrate,
and a photoelectric conversion material layer 30 is formed on the
region of the substrate 20B extending from the first electrode 21B
to the second electrode 22B. Light enters the photoelectric
conversion material layer 30 through the second electrode 22B.
Alternatively, light enters the photoelectric conversion material
layer 30 through the substrate 20B or the first electrode 21B.
Specifically, the substrate 20B is made, for example, of a silicon
semiconductor substrate; the first electrode 21B and the second
electrode 22B are made of a metal material or a transparent
conductive material. Excepts for these points above, the
configuration and the structure of the photoelectric conversion
element 13 or the photoelectric conversion apparatus of Example 4
are similar to those of the photoelectric conversion element 11 or
the photoelectric conversion apparatus in Example 1 or Example 2,
and no detailed description thereof is provided.
Example 5
[0110] Example 5 is also a variation of Example 1 or Example 2. In
Examples 1 to 4, the photoelectric conversion element has a
two-terminal electronic device structure having the first electrode
21 and the second electrode 22. Alternatively in Example 5 and
Examples 6 to 8 described below, the photoelectric conversion
element has a three-terminal electronic device structure
additionally having a control electrode. It is possible to modulate
the flow of electric current by application of voltage to the
control electrode. In Example 5, specifically, the configuration
and the structure identical with those of a bottom gate/bottom
contact-type FET were used for the three-terminal electronic device
structure.
[0111] More specifically, as shown in the partial schematic
cross-sectional view of FIG. 7A, a photoelectric conversion element
14 of Example 5 in the bottom gate/bottom contact-type
three-terminal electronic device structure has
[0112] (a) a control electrode formed on a support 113
(corresponding to a gate electrode 114),
[0113] (b) an insulation layer formed on the control electrode
(gate electrode 114) and the support 113 (corresponding to gate
insulation layer 115),
[0114] (c) first and second electrodes formed on the insulation
layer (gate insulation layer 115) (corresponding to source and
drain electrodes 116), and
[0115] (d) a photoelectric conversion material layer formed on the
insulation layer (gate insulation layer 115) between the first and
second electrodes (source and drain electrodes 116) (corresponding
to a channel forming region 117).
[0116] The control electrode (gate electrode 114) is made of gold;
the insulation layer (gate insulation layer 115) is made of
SiO.sub.2; and the support 113 is made of a silicon semiconductor
substrate 111 and an insulation film 112 formed thereon. The first
and second electrodes (source and drain electrodes 116) and the
photoelectric conversion material layer (channel forming region
117) are made of the materials identical with those for the first
electrode 21B, the second electrode 22B, and the photoelectric
conversion material layer 30 in Example 4. In addition, the first
and second electrodes (source and drain electrodes 116) are
connected to a current detection circuit 40 not shown in the
Figure. The same shall apply in the following Examples.
[0117] Hereinafter, the method of producing the photoelectric
conversion element 14 of Example 5 will be described briefly.
[0118] [Step 500]
[0119] First, a gate electrode 114 is formed on a support 113.
Specifically, a resist layer in which the region for the gate
electrode 114 is previously removed (not shown in the Figure) is
formed on the insulation film 112 by lithographic method. Then, a
chromium (Cr) layer as an adhesion layer (not shown in the Figure)
and a gold (Au) layer as the gate electrode 114 are formed one by
one on the entire surface by vacuum deposition, and then, the
resist layer is removed. It is possible in this way to obtain a
gate electrode 114 by the so-called lift off method.
[0120] [Step 510]
[0121] Subsequently, a gate insulation layer 115 is formed on the
support 113 carrying the gate electrode 114. Specifically, a gate
insulation layer 115 of SiO.sub.2 is formed on the gate electrode
114 and insulation film 112 by sputtering method. When the gate
insulation layer 115 is formed, it is possible to form the
connection region of the gate electrode 114 (not shown in the
Figure) without photolithographic processing by covering part of
the gate electrode 114 with a hard mask.
[0122] [Step 520]
[0123] Source and drain electrodes 116 are formed on the gate
insulation layer 115. Specifically, a resist layer in which the
regions for the source and drain electrodes 116 are previously
removed is formed on the gate insulation layer 115 by lithographic
method. The source and drain electrodes 116 are formed sequentially
by vacuum deposition method and then, the resist layer is removed.
It is possible in this way to obtain source and drain electrodes
116 by the so-called lift-off method.
[0124] [Step 530]
[0125] Subsequently, a channel forming region 117 is formed on the
gate insulation layer 115 in a manner similar to Example 1 or
Example 2.
[0126] [Step 540]
[0127] Finally, an insulating material layer as a passivation layer
(not shown in the Figure) is formed on the entire surface; openings
are formed in the insulating material layer above the source and
drain electrodes 116; a wiring material layer is formed on the
entire surface thereof including the areas in the openings; and a
photoelectric conversion element 14 having a bottom gate/bottom
contact-type FET (TFT) structure, which has wirings (not shown in
the Figure) connected to the source and drain electrodes 116 formed
on the insulating material layer, is formed by patterning the
wiring material layer.
Example 6
[0128] Specifically in Example 6, the structure and the
configuration identical with those of the bottom gate/top
contact-type FET was used as the three-terminal electronic device
structure.
[0129] More specifically, as shown in the partial schematic
cross-sectional view of FIG. 7B, a photoelectric conversion element
15 of Example 6 having a bottom gate/top contact-type
three-terminal electronic device structure has
[0130] (a) a control electrode formed on a support 113
(corresponding to a gate electrode 114),
[0131] (b) an insulation layer formed on the control electrode
(gate electrode 114) and the support 113 (corresponding to gate
insulation layer 115),
[0132] (c) a photoelectric conversion material layer (corresponding
to channel forming region 117) and a peripheral region of the
photoelectric conversion material layer 118 formed on the
insulation layer (gate insulation layer 115), and
[0133] (d) a first electrode/a second electrode formed on the
peripheral region of the photoelectric conversion material layer
118 (corresponding to source and drain electrodes 116).
[0134] Hereinafter, the method of producing the photoelectric
conversion element 15 of Example 6 will be described briefly.
[0135] [Step 600]
[0136] First, a gate electrode 114 is formed on a support 113
(insulation film 112), in a similar manner to [Step 500] of Example
5; and a gate insulation layer 115 is formed on the gate electrode
114 and the insulation film 112, in a similar manner to [Step
510].
[0137] [Step 610]
[0138] A channel forming region 117 and the peripheral region of
the channel forming region 118 are then formed on the gate
insulation layer 115 by a method similar to that in [Step 530].
[0139] [Step 620]
[0140] Source and drain electrodes 116 are then formed on the
peripheral region of the channel forming region 118 as they hold
the channel forming region 117 between them, similarly to [Step
520] in Example 5. However, it is possible to form the source and
drain electrodes 116 without photolithographic processing, by
covering the channel forming region 117 with a hard mask during
formation of the source and drain electrodes 116.
[0141] [Step 630]
[0142] Finally, it is possible to obtain a photoelectric conversion
element 15 having a bottom gate/top contact-type FET (TFT)
structure by processing in a step similar to [Step 540].
Example 7
[0143] Specifically in Example 7, the configuration and structure
identical with those of the top gate/bottom contact-type FET were
used as the three-terminal electronic device structure.
[0144] More specifically, as shown in the partial schematic
cross-sectional view of FIG. 7A, a photoelectric conversion element
16 of Example 8A having a top gate/bottom contact-type
three-terminal electronic device structure has:
[0145] (a) a first electrode/a second electrode formed on a support
113 (corresponding to source and drain electrodes 116),
[0146] (b) a photoelectric conversion material layer (corresponding
to channel forming region 117) formed on the support 113 between
the first and second electrodes (source and drain electrodes
116),
[0147] (c) an insulation layer formed on the first and second
electrodes (source and drain electrodes 116) and the photoelectric
conversion material layer (channel forming region 117)
(corresponding to gate insulation layer 115), and
[0148] (d) a control electrode formed on the insulation layer (gate
insulation layer 115) (corresponding to gate electrode 114).
[0149] Hereinafter, the method of producing the photoelectric
conversion element 16 of Example 7 will be described briefly.
[0150] [Step 700]
[0151] First, source and drain electrodes 116 are formed on a
support 113, in a similar manner to [Step 520] of Example 5.
[0152] [Step 710]
[0153] A channel forming region 117 is then formed on the support
113 (insulation film 112) between the source and drain electrodes
116 by a method similar to that of [Step 530]. In practice, the
peripheral region of the channel forming region 118 is formed on
the source and drain electrodes 116.
[0154] [Step 720]
[0155] A gate insulation layer 115 is then formed on the source and
drain electrodes 116 and the channel forming region 117 (in
practice, on the channel forming region 117 and the peripheral
region of the channel forming region 118). Specifically, it is
possible to obtain a gate insulation layer 115 by coating PVA on
the entire surface by a spin coating method.
[0156] [Step 730]
[0157] A gate electrode 114 is then formed on the gate insulation
layer 115. Specifically, a chromium (Cr) layer as adhesion layer
(not shown in the Figure), and a gold (Au) layer as gate electrode
114 are formed on the entire surface sequentially by a vacuum
deposition method. It is possible to form the gate electrode 114
without photolithographic processing, by covering part of the gate
insulation layer 115 with a hard mask during formation of the gate
electrode 114. Finally, it is possible to obtain a photoelectric
conversion element 16 having a top gate/bottom contact-type FET
(TFT) structure, by processing in a step similar to [Step 540].
Example 8
[0158] Specifically in Example 8, the configuration and the
structure identical with those of the top gate/top contact-type FET
was used as the three-terminal electronic device structure.
[0159] More specifically, as shown in the partial schematic
cross-sectional view of FIG. 8B, a photoelectric conversion element
17 of Example 8 having a top gate/top contact-type three-terminal
electronic device structure has
[0160] (a) a photoelectric conversion material layer (corresponding
to channel forming region 117) and the peripheral region of the
photoelectric conversion material layer 118 formed on a support
113,
[0161] (b) a first electrode and a second electrode formed on the
peripheral region of the photoelectric conversion material layer
118 (corresponding to source and drain electrodes 116),
[0162] (c) an insulation layer formed on the first and second
electrodes (source and drain electrodes 116) and the photoelectric
conversion material layer (channel forming region 117)
(corresponding to gate insulation layer 115), and
[0163] (d) a control electrode formed on the insulation layer (gate
insulation layer 115) (corresponding to gate electrode 114).
[0164] Hereinafter, the method of producing the photoelectric
conversion element 17 of Example 8 will be described briefly.
[0165] [Step 800]
[0166] First, the channel forming region 117 and the peripheral
region of the channel forming region 118 are formed on the support
113 by a method similar to that in [Step 530].
[0167] [Step 810]
[0168] Source and drain electrodes 116 are then formed on the
peripheral region of the channel forming region 118 as they hold
the channel forming region 117 between them, in a similar manner to
[Step 520] in Example 5. It is possible to form the source and
drain electrodes 116 without photolithographic processing, by
covering the channel forming region 117 with a hard mask during
formation of the source and drain electrodes 116.
[0169] [Step 820]
[0170] A gate insulation layer 115 is then formed on the source and
drain electrodes 116 and the channel forming region 117.
Specifically, it is possible to obtain a gate insulation layer 115
by coating the entire surface with PVA by spin coating method.
[0171] [Step 830]
[0172] A gate electrode 114 is then formed on the gate insulation
layer 115, in a similar manner to [Step 730] of Example 7. It is
possible, by finally executing processing in a step similar to
[Step 540], to obtain a photoelectric conversion element 17 having
a top gate/top contact-type FET (TFT) structure.
Example 9
[0173] Example 9 relates to a solid-state imaging apparatus having
one of the photoelectric conversion apparatuses or photoelectric
conversion elements described in Examples 1 to 4.
[0174] FIG. 9 is a schematic diagram showing the solid-state
imaging apparatus (solid-state imaging element) of Example 9. A
solid-state imaging apparatus 50 of Example 9 has an imaging region
51 including photoelectric conversion elements 60 described in any
one of Examples 1 to 4 (photoelectric conversion elements 11, 12 or
13) aligned in a two-dimensional array on a semiconductor substrate
(such as Si substrate), and peripheral circuits such as a vertical
drive circuit 52, a column signal-processing circuit 53, a
horizontal drive circuit 54, an output circuit 55, and a control
circuit 56. These circuits may be formed with known circuits or
circuits with different circuit configurations (for example,
various circuits used in known CCD and CMOS imaging
apparatuses).
[0175] The control circuit 56 generates clock and control signals,
standards of operation of the vertical drive circuit 52, the column
signal-processing circuit 53, and the horizontal drive circuit 54,
based on vertically synchronized signal, horizontally synchronized
signal, and master clock. The generated clock and control signals
are inputted into the vertical drive circuit 52, the column
signal-processing circuit 53, and the horizontal drive circuit
54.
[0176] The vertical drive circuit 52, which has, for example, shift
registers, selects and scans the photoelectric conversion elements
60 in the imaging region 51 sequentially by line in a vertical
direction. A pixel signal based on the electric current (signal)
generated according to the intensity of the light received in each
photoelectric conversion element 60 is transmitted to the column
signal-processing circuit 53 via a vertical signal wire 57.
[0177] The column signal-processing circuit 53, which is installed,
for example, in every line of the photoelectric conversion elements
60, processes the signals outputted from the photoelectric
conversion elements 60 in each line for removal of noises and
amplification of signal in each photoelectric conversion element,
based on the signal from black standard pixel (not shown in the
Figure, formed in the region surrounding the effective pixel
region). In the output stage of the column signal-processing
circuit 53, a horizontal selection switch (not shown in the Figure)
is installed as it is connected to a horizontal signal wire 58.
[0178] The horizontal drive circuit 54, which has, for example,
shift registers, sequentially selects each of the column
signal-processing circuits 53 by outputting horizontal scanning
pulses sequentially and outputs a signal from each of the column
signal-processing circuits 53 to the horizontal signal wire 58.
[0179] The output circuit 55 processes the signal sequentially
transmitted from each of the column signal-processing circuits 53
via the horizontal signal wire 58 and outputs the processed
signal.
[0180] An example of part of the current detection circuit 40 is
shown in FIG. 10. A current detection circuit 40 is formed, for
example, for one line of photoelectric conversion elements 60. The
current detection circuit 40 is formed in the column
signal-processing circuit 53. Alternatively, a current detection
circuit 40 may be formed for each photoelectric conversion element
60. In the current detection circuit 40 shown in FIG. 10, the
electric potential generated at the terminal of resistor by the
electric current generated in the photoelectric conversion element
60 is converted into voltage, as it is inputted into a
non-inverting amplifier. It The current detection circuit 40 shown
in FIG. 10 is applicable to other Examples and also that current
detection circuits in other configuration or structure can also be
used.
[0181] Although it depends on the materials constituting the
photoelectric conversion material layer, the photoelectric
conversion material layer itself may have a function as color
filter, and thus color separation is possible even if no color
filter is formed. A known color filter permitting transmission of
particular wavelength such as red, green, blue, cyan, magenta or
yellow may be installed as needed above a light-entering side of
the photoelectric conversion element 60. In addition, the
solid-state imaging apparatus may be a front-face irradiation-type
apparatus or a rear-face irradiation-type apparatus. A shutter for
control of the incident light into the photoelectric conversion
element 60 may also be formed as needed.
[0182] The structure, configuration, production condition,
production method, and materials used of the photoelectric
conversion apparatuses, the photoelectric conversion elements, and
the solid-state imaging apparatuses described in Examples are
nothing but examples, and may be modified as needed. For operation
of the photoelectric conversion apparatus according to the
embodiment as a photovoltaic cell, the photoelectric conversion
material layer is irradiated with light while no voltage is applied
between the first electrode and the second electrode. In such a
case, the current detection circuit for detection of the current
generated in the photoelectric conversion material layer may not be
necessary.
[0183] It should be understood that various changes and
modifications to the presently preferred embodiments described
herein will be apparent to those skilled in the art. Such changes
and modifications can be made without departing from the spirit and
scope of the present subject matter and without diminishing its
intended advantages. It is therefore intended that such changes and
modifications be covered by the appended claims.
* * * * *