U.S. patent application number 12/668420 was filed with the patent office on 2010-08-05 for solar cell and method of manufacturing the same.
This patent application is currently assigned to JUSUNG ENGINEERING CO., LTD.. Invention is credited to Jin Hong, Jae Ho Kim, Chang Sil Yang.
Application Number | 20100193022 12/668420 |
Document ID | / |
Family ID | 40229281 |
Filed Date | 2010-08-05 |
United States Patent
Application |
20100193022 |
Kind Code |
A1 |
Hong; Jin ; et al. |
August 5, 2010 |
SOLAR CELL AND METHOD OF MANUFACTURING THE SAME
Abstract
Provided are a solar cell and a method of manufacturing the
same. The solar cell includes a transparent substrate. A first
electrode and a transparent insulating layer are sequentially
stacked over a plurality of first regions of the transparent
substrate. A first electrode, a light-converting layer, a
transparent insulating layer, and a second electrode are
sequentially stacked over a second region of the transparent
substrate other than the first regions. Therefore, light incident
from the substrate can penetrate between the light-converting
layers spaced apart from each other, thus manufacturing a
transparent solar cell. Also, since light scattered by the
transparent insulating layer is also incident into the side of the
light-converting layer, the light-receiving area is not reduced and
thus the efficiency of the solar cell can be increased.
Inventors: |
Hong; Jin; (Gyeonggi-Do,
KR) ; Kim; Jae Ho; (Gyeonggi-Do, KR) ; Yang;
Chang Sil; (Gyeonggi-Do, KR) |
Correspondence
Address: |
HOSOON LEE
9600 SW OAK ST. SUITE 525
TIGARD
OR
97223
US
|
Assignee: |
JUSUNG ENGINEERING CO.,
LTD.
Gyeonggi-Do
KR
|
Family ID: |
40229281 |
Appl. No.: |
12/668420 |
Filed: |
July 10, 2008 |
PCT Filed: |
July 10, 2008 |
PCT NO: |
PCT/KR08/04061 |
371 Date: |
January 26, 2010 |
Current U.S.
Class: |
136/256 ;
257/E31.127; 438/69 |
Current CPC
Class: |
H01L 31/075 20130101;
Y02E 10/548 20130101; H01L 31/0468 20141201; H01L 31/18 20130101;
H01L 31/02167 20130101; Y02P 70/50 20151101; H01L 31/035281
20130101; H01L 31/02363 20130101; H01L 31/202 20130101; Y02P 70/521
20151101; H01L 31/022433 20130101 |
Class at
Publication: |
136/256 ; 438/69;
257/E31.127 |
International
Class: |
H01L 31/00 20060101
H01L031/00; H01L 31/0232 20060101 H01L031/0232; H01L 31/18 20060101
H01L031/18 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 10, 2007 |
KR |
10-2007-0069255 |
Claims
1. A solar cell, comprising: a transparent substrate; a first
electrode and a transparent insulating layer that are sequentially
stacked over a plurality of first regions of the transparent
substrate; and a first electrode, a light-converting layer, a
transparent insulating layer, and a second electrode that are
sequentially stacked over a second region of the transparent
substrate other than the first regions.
2-20. (canceled)
21. The solar cell of claim 1, wherein the transparent insulating
layer is formed to have a thickness that allows tunneling and
insulating characteristics.
22. The solar cell of claim 21, wherein the transparent insulating
layer is further formed over a sidewall of the light-converting
layer.
23. The solar cell of claim 22, wherein the transparent insulating
layer is continuously formed over an upper surface and the sidewall
of the plurality of light-converting layers which is spaced apart
from each other.
24. The solar cell of claim 23, wherein the transparent insulating
layer is formed using ZnO.
25. The solar cell of claim 1, wherein the second electrode is
formed to have a thickness capable of transmitting light and
functioning as an electrode.
26. The solar cell of claim 1, wherein light incident onto the
sidewalls of the light-converting layer is received to the solar
cell.
27. The solar cell of claim 26, further comprising an insulating
layer that is formed over the sidewall of the light-converting
layer and scatters the incident light for the light to be absorbed
to the sidewall of the light-converting layer.
28. A solar cell, comprising: a transparent substrate; a first
electrode, a transparent insulating layer, and a second electrode
that are sequentially stacked over a plurality of first regions of
the transparent substrate: and a first electrode, a
light-converting layer, a transparent insulating layer, and a
second electrode that are sequentially stacked over a second region
of the transparent substrate other than the first regions.
29. The solar cell of claim 28, wherein the transparent insulating
layer is formed to have a thickness that allows tunneling and
insulating characteristics.
30. The solar cell of claim 29, wherein the transparent insulating
layer is further formed over a sidewall of the light-converting
layer.
31. The solar cell of claim 30, wherein the transparent insulating
layer is continuously formed over an upper surface and the sidewall
of the plurality of light-converting layers which is spaced apart
from each other.
32. The solar cell of claim 31, wherein the transparent insulating
layer is formed using ZnO.
33. The solar cell of claim 28, wherein the second electrode is
formed to have a thickness capable of transmitting light and
functioning as an electrode.
34. The solar cell of claim 28, wherein light incident onto the
sidewalls of the light-converting layer is received to the solar
cell.
35. The solar cell of claim 34, further comprising an insulating
layer that is formed over the sidewall of the light-converting
layer and scatters the incident light for the light to be absorbed
to the sidewall of the light-converting layer.
36. The solar cell of claim 28, wherein the second electrode of the
first region is formed of aluminum or silver.
37. A method of manufacturing a solar cell, the method comprising:
forming a first electrode over a substrate; forming a
light-converting layer over the first electrode and patterning the
light-converting layer to form a plurality of patterned
light-converting layers that are spaced apart from each other;
forming a transparent insulating layer over the first electrode
including the patterned light-converting layers: and forming a
second electrode over the transparent insulating layer.
38. The method of claim 37, wherein the transparent insulating
layer is formed by depositing ZnO using a MOCVD (Metal-Organic
Chemical Vapor Deposition) process or a sputtering process
39. The method of claim 37, wherein the second electrode is formed
of a metallic material using a PECVD (Plasma-Enhanced Chemical
Vapor Deposition) process or sputtering process, and formed to have
a thickness capable of transmitting light and functioning as an
electrode.
40. The method of claim 39, wherein the second electrode is formed
using silver or aluminum such that the second electrode has a
smaller pattern than the patterned light-converting layer.
41. The method of claim 37, wherein the first electrode, the
light-converting layer, the transparent insulating layer and the
second electrode are formed in separate chambers, respectively, or
continuously formed in the same chamber by controlling input
gas.
42. The method of claim 41, wherein the same chamber is a PECVD
(Plasma-Enhanced Chemical Vapor Deposition) chamber.
43. The method of claim 37, wherein the transparent insulating
layer is further formed over a sidewall of the light-converting
layer.
44. The method of claim 43, wherein the transparent insulating
layer is continuously formed over an upper surface and the sidewall
of the plurality of light-converting layers which is spaced apart
from each other.
45. The method of claim 37, wherein light incident onto the
sidewall of the light-converting layer is received to the solar
cell.
46. The method of claim 45, further comprising forming an
insulating layer over the sidewall of the light-converting layer to
scatter the incident light such that the light is absorbed to the
sidewall of the light-converting layer.
Description
TECHNICAL FIELD
[0001] The present invention relates to a solar cell and a method
of manufacturing the same, and more particularly, to a transparent
solar cell capable of transmitting light without reducing a
light-receiving area and a method of manufacturing the same.
BACKGROUND ART
[0002] Recently, with the increase in concern about environmental
problems and energy depletion, a solar cell is attracting an
increasing attention as an alternative energy source that has
abundant energy resources, has no environmental pollution problem,
and has high energy efficiency. Solar cells can be classified into
a solar heat cell and a solar light cell. The solar heat cell uses
solar heat to generate steam necessary for rotating a turbine. The
solar light cell uses semiconductor materials to convert solar
light into electrical energy.
[0003] The solar light cell can be generally classified into a
crystalline silicon solar cell and a thin film solar cell. The
crystalline silicon solar cell includes a polycrystalline silicon
solar cell and a single crystalline silicon solar cell. The thin
film solar cell includes an amorphous silicon solar cell. However,
since the crystalline silicon solar cell is manufactured using an
expensive thick silicon substrate, the crystalline silicon solar
cell has a limitation in reducing its thickness. Furthermore, since
the silicon substrate is expensive, a price of the crystalline
silicon solar cell becomes high.
[0004] What is thus being in the spotlight is the amorphous silicon
solar cell that can be manufactured at a lot cost because it uses
an inexpensive substrate such as a glass substrate and a metal
substrate instead of an expensive silicon substrate and minimizes
material consumption by depositing a thin film of several
microns.
[0005] In comparison with the single crystalline silicon substrate
or the polycrystalline silicon substrate, an amorphous-silicon thin
film has a very short carrier diffusion length due to its inherent
characteristics. Therefore, when forming a PN structure using the
amorphous-silicon thin film, the efficiency of collecting
electron-hole pairs may be very low. Thus, the amorphous silicon
solar cell uses a light-converting layer of a PIN structure that
has a highly-doped p-type amorphous silicon layer, a highly-doped
n-type amorphous silicon layer, and an undoped i-type amorphous
silicon layer inserted between the highly-doped p-type amorphous
silicon layer and the highly-doped n-type amorphous silicon layer,
and the amorphous silicon solar cell generally includes a first
electrode, a PIN light-converting layer, and a second electrode,
which are sequentially stacked over a substrate.
[0006] However, even when the amorphous silicon solar cell uses a
transparent glass substrate, it fails to transmit light incident
from the glass substrate since the amorphous silicon solar cell
becomes opaque by the PIN light-converting layer and the electrodes
are formed over the glass substrate. What is thus manufactured is a
transparent solar cell as illustrated in FIGS. 1 and 2. As
illustrated in FIGS. 1 and 2, a related art transparent solar cell
includes a first electrode 20, a light-converting layer 30, an
insulating layer 40, and a second electrode 50 that are stacked
over a transparent substrate 10, and has a through hole 60 formed
from the substrate 10 to a pre-determined region of the second
electrode 50, thus transmitting light from the bottom of the
transparent substrate 10 via the through hole 60. The
light-converting layer 30 includes a stack of a p-type amorphous
silicon layer 31, an i-type amorphous silicon layer 32, and an
n-type amorphous silicon layer 33.
[0007] However, when the through hole 60 is formed from the bottom
of the transparent substrate 10 to the predetermined region of the
second substrate 50, the light-absorbing area is reduced and thus
the efficiency of the solar cell is deteriorated.
DISCLOSURE OF INVENTION
Technical Problem
[0008] The present invention provides a transparent solar cell
capable of transmitting light without deteriorating the efficiency
thereof by not reducing a light-receiving area, and a method of
manufacturing the same.
[0009] The present invention also provides a transparent solar cell
capable of transmitting light without reducing a light-receiving
area, and a method of manufacturing the same. To this end,
light-converting layers are patterned, a transparent insulating
layer is formed thinly, and an electrode is formed, so that light
can penetrate between the light-converting layers and light can be
incident also onto the sides of the light-converting layers.
Technical Solution
[0010] In accordance with one aspect of the present invention, a
solar cell includes: a transparent substrate; a first electrode and
a transparent insulating layer that are sequentially stacked over a
plurality of first regions of the transparent substrate; and a
first electrode, a light-converting layer, a transparent insulating
layer, and a second electrode that are sequentially stacked over a
second region of the transparent substrate other than the first
regions.
[0011] In accordance with another aspect of the present invention,
a solar cell includes: a transparent substrate; a first electrode,
a transparent insulating layer, and a second electrode that are
sequentially stacked over a plurality of first regions of the
transparent substrate; and a first electrode, a light-converting
layer, a transparent insulating layer, and a second electrode that
are sequentially stacked over a second region of the transparent
substrate other than the first regions.
[0012] The first electrode may be formed of transparent conductive
materials.
[0013] The light-converting layer may include a stack structure of
a first semiconductor layer that is doped with first impurities, a
second semiconductor layer that is not doped with impurities, and a
third semiconductor layer that is doped with second impurities.
[0014] The transparent insulating layer may include a ZnO
layer.
[0015] The ZnO transparent insulating layer may be formed to a
thickness that provides the ZnO layer with tunneling and insulating
characteristics.
[0016] The ZnO transparent insulating layer may be formed to a
thickness of approximately 1000 .ANG. or less.
[0017] In accordance with still another aspect of the present
invention, a method of manufacturing a solar cell includes: forming
a first electrode over a substrate; forming a light-converting
layer over the first electrode and patterning the light-converting
layer to form a plurality of patterned light-converting layers
spaced apart from each other; forming a transparent insulating
layer over the first electrode including the patterned
light-converting layers; and forming a second electrode over the
transparent insulating layer.
[0018] The light-converting layer may be patterned by a dry etching
process using a gas obtained by mixing one of NF.sub.3, SF.sub.6,
HBr, Cl.sub.2, BCl.sub.3 and a combination thereof with one of Ar,
O.sub.2, He, N.sub.2 and a combination thereof.
[0019] The transparent insulating layer may be formed by depositing
ZnO using a metal-organic chemical vapor deposition (MOCVD) process
or a sputtering process.
[0020] The second electrode may be formed of silver to a thickness
of approximately 500 .ANG. or less using a sputtering process.
[0021] The second electrode may be formed of aluminum over the
transparent insulating layer that is formed over the
light-converting layer such that that the second electrode has a
smaller pattern than the patterned light-converting layer.
Advantageous Effects
[0022] As described above, the present invention forms the
plurality of light-converting layers spaced apart from each other,
forms the transparent insulating layer, and then forms the second
electrode. Therefore, light incident from the substrate can
penetrate between the light-converting layers, thus manufacturing a
transparent solar cell. Also, since light scattered by the
transparent insulating layer is incident also onto the sides of the
light-converting layers, the light-receiving area is not reduced
and thus the efficiency of the solar cell is increased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a cross-sectional view of a related art
transparent solar cell;
[0024] FIG. 2 is a cutaway perspective view of the related art
transparent solar cell;
[0025] FIG. 3 is a plan view of a solar cell in accordance with a
first embodiment of the present invention;
[0026] FIG. 4 is a cutaway perspective view of the solar cell in
accordance with the first embodiment of the present invention;
[0027] FIG. 5 is a cross-sectional view of the solar cell in
accordance with the first embodiment of the present invention;
[0028] FIG. 6 is a block diagram of a cluster used to manufacture
the solar cell in accordance with the first embodiment of the
present invention;
[0029] FIGS. 7 to 10 are cross-sectional views illustrating a
method of manufacturing the solar cell in accordance with the first
embodiment of the present invention;
[0030] FIG. 11 is a plan view of a solar cell in accordance with a
second embodiment of the present invention;
[0031] FIG. 12 is a cutaway perspective view of the solar cell in
accordance with the second embodiment of the present invention;
[0032] FIG. 13 is a cross-sectional view of the solar cell in
accordance with the second embodiment of the present invention;
and
[0033] FIGS. 14 to 17 are cross-sectional views illustrating a
method of manufacturing the solar cell in accordance with the
second embodiment of the present invention.
MODE FOR THE INVENTION
[0034] Hereinafter, specific embodiments will be described in
detail with reference to the accompanying drawings. The present
invention may, however, be embodied in different forms and should
not be construed as limited to the embodiments set forth herein.
Rather, these embodiments are provided so that this disclosure will
be thorough and complete, and will fully convey the scope of the
present invention to those skilled in the art.
[0035] FIG. 3 is a plan view of a solar cell in accordance with a
first embodiment of the present invention. FIG. 4 is a cutaway
perspective view of the solar cell in accordance with the first
embodiment of the present invention. FIG. 5 is a cross-sectional
view taken along a line A-A' of FIG. 3.
[0036] Referring to FIGS. 3 to 5, a first electrode 120 is formed
over a substrate 110, and a plurality of light-converting layers
130 are formed over the first electrode 120 in such a way that they
are spaced apart from each other. Also, a transparent insulating
layer 140 is formed over a resulting structure including the
light-converting layers 130, and a second electrode 150 is formed
over the transparent insulating layer 140 that is formed over the
light-converting layer 130.
[0037] The substrate 110 may be a transparent substrate. Examples
of the transparent substrate are a plate-shaped substrate and a
sheet-shaped substrate that are formed of glass or transparent
resin. A fine irregular structure may be formed in a surface of the
substrate 110. The fine irregular surface structure of the
substrate 110 can increase the absorption of incident light.
[0038] The first electrode 120 may be formed of transparent
conductive materials such as indium tin oxide (ITO) and indium zinc
oxide (IZO). Also, the first electrode 120 may have a fine
irregular structure formed in a surface thereof.
[0039] The light-converting layer 130 is formed in plurality spaced
apart from each other. Each of the light-converting layers 130
includes a plurality of semiconductor layers. For example, each of
the light-converting layers 130 includes a stack of a p-type
amorphous silicon layer 131, an i-type amorphous silicon layer 132,
and an n-type amorphous silicon layer 133. Herein, the p-type
amorphous silicon layer 131 is a layer that is doped with p-type
impurities, the i-type amorphous silicon layer 132 is a layer that
is not doped with impurities, and the n-type amorphous silicon
layer 133 is a layer that is doped with n-type impurities. For
example, the p-type amorphous silicon layer 131 is formed using
B.sub.2H.sub.6 gas and SiH.sub.4 gas, the i-type amorphous silicon
layer 132 is formed using H.sub.2 gas and SiH.sub.4 gas, and the
n-type amorphous silicon layer 133 is formed using PH.sub.3 gas and
SiH.sub.4 gas. Also, the p-type amorphous silicon layer 131 is
formed to a thickness of approximately 100 .ANG. to approximately
200 .ANG., the i-type amorphous silicon layer 132 is formed to a
thickness of approximately 4000 .ANG. to approximately 5000 .ANG.
and the n-type amorphous silicon layer 133 is formed to a thickness
of approximately 500 .ANG. to approximately 700 .ANG.. When light
is incident on the i-type amorphous silicon layer 132 of the
light-converting layer 130, each of stable electron-hole pairs in
the i-type amorphous silicon layer 132 is discomposed by photons to
generate an electron and a hole. The generated electron and the
hole are respectively transferred through the n-type amorphous
silicon layer 133 and the p-type amorphous silicon layer 131 to the
second electrode 150 and the first electrode 120. The transfer of
the electron and the hole generates photovoltaic power that becomes
the electrical energy of the solar cell.
[0040] The transparent insulating layer 140 is formed over the
resulting structure including the light-converting layers 130.
Thus, the transparent insulating layer 140 is also formed over the
sidewalls of the light-converting layers 130 to insulate the
light-converting layers 130. The transparent insulating layer 140
may be formed to a thickness that allows the tunneling of electrons
passing through the n-type amorphous silicon layer 133. For
example, the transparent insulating layer 140 may include a ZnO
layer. The ZnO layer is an n-type semiconductor material when not
doped with impurities, and has insulating characteristics when
having a small thickness of approximately 1000 .ANG. or less. Thus,
using the ZnO layer, the transparent insulating layer 140 is formed
to a thickness of approximately 1000 .ANG. or less, which can allow
the tunneling and have insulating characteristics.
[0041] The second electrode 150 is formed in a smaller pattern than
the light-converting layer 130, over the transparent insulating
layer 140 that is formed over the light-converting layer 130. The
received light quantity increases as the second electrode 150 is
formed smaller than the light-converting layer 130. The second
electrode 150 is formed in plurality spaced apart from each other.
The second electrode 150 is formed mainly of metal, for example,
aluminum (Al).
[0042] The solar cell in accordance with the first embodiment
includes: a plurality of first regions where the first electrode
120 and the transparent insulating layer 140 are stacked over the
substrate 110; and a plurality of second regions where the first
electrode 120, the light-converting layer 130, the transparent
insulating layer 140, and the second electrode 150 are stacked over
the substrate 110. The solar cell can transmit light incident from
the bottom surface of the substrate 110 through the first region,
so that it possible to embody a transparent solar cell. Herein, the
distance between the first electrode 120 and the second electrode
150 in the first region is greater than the distance between the
first electrode 120 and the second electrode 150 in the second
region. Also, since incident light is scattered by the transparent
insulating layer 140 and thus light is absorbed also onto the side
of the light-converting layer 130, the light-receiving area is not
reduced and thus it possible to increase the efficiency of the
solar cell.
[0043] FIG. 6 is a block diagram of a cluster equipment used to
manufacture the solar cell in accordance with the first embodiment
of the present invention.
[0044] Referring to FIG. 6, the cluster equipment includes a
load-lock chamber 100, first to seventh process chambers 200 to
800, and a transfer chamber 900. The first process chamber 200 is
used to form the first electrode 120 and may be configured to
include a plasma-enhanced chemical vapor deposition (PECVD)
chamber. The second to fourth process chambers 300 to 500 are used
to sequentially form the p-type amorphous silicon layer 131, the
i-type amorphous silicon layer 132, and the n-type amorphous
silicon layer 133 that constitute the light-converting layer 130.
For example, each of the second to fourth process chambers 300 to
500 is configured to include a PECVD chamber. The fifth process
chamber 600 is used to etch the light-converting layer 130 in a
predetermined pattern and may be configured to include a dry
etching chamber. The sixth process chamber 700 is used to form the
transparent insulating layer 140 and may be configured to include a
metal-organic chemical vapor deposition (MOCVD) chamber. The
seventh process chamber 800 is used to form the second electrode
150 and may be configured to include a PECVD chamber or a
sputtering chamber. The transfer chamber 900 is used to transfer a
wafer from each chamber to the next chamber.
[0045] The cluster equipment may change in configuration. For
example, although it has been described that the light-converting
layer 130 is formed using the second, third and fourth process
chambers 300, 400 and 500, the light-converting layer 130 may be
formed by using one of the second, third and fourth process
chambers 300, 400 and 500 and controlling process gas that flows
into the process chamber. Also, the chambers may change in
arrangement. Also, the cluster equipment may further include: a
deposition device for depositing a photoresist layer; an
exposure/development device for patterning the photoresist layer;
an ashing device for removing the photoresist layer; and a cleaning
device.
[0046] FIGS. 7 to 10 are cross-sectional views illustrating a
method of manufacturing the solar cell in accordance with the first
embodiment by using the cluster equipment of FIG. 6. FIGS. 7 to 10
are cross-sectional views taken along the line A-A' of FIG. 3.
[0047] Referring to FIG. 7, the transparent substrate 110 formed of
glass or transparent resin is loaded into the load-lock chamber
100, and the load-lock chamber 100 loaded with the transparent
substrate 110 is loaded into the first process chamber 200. In the
first process chamber 200, transparent conductive material such as
indium tin oxide (ITO) and indium zinc oxide (IZO) is formed over
the transparent substrate 110, thereby forming the first electrode
120 over the transparent substrate 110. Herein, the transparent
substrate 110 or the first electrode 120 may have a fine irregular
structure formed in a surface thereof. The fine irregular structure
may be formed performing a plasma-based dry etching process, a
mechanical scribing process, or a wet etching process. When the
fine irregular structure is formed, light is bounded against the
surface of the fine irregular structure two or more times, thus
making it possible to reduce the light reflection and increase the
light absorption. Also, the fine irregular structure is formed in
the transparent substrate 110 and then the first electrode 120 is
formed along the irregular structure of the transparent substrate
110, so that both of the transparent substrate 110 and the first
electrode 120 can have the irregular structure. Using the transfer
chamber 900, the transparent substrate 110 having the first
electrode 120 formed thereon is sequentially loaded into the
second, third and fourth process chambers 300, 400 and 500, thereby
forming the light-converting layer 130, which includes the stack of
the p-type amorphous silicon layer 131, the i-type amorphous
silicon layer 132, and the n-type amorphous silicon layer 133, over
the first electrode 120. For example, the light-converting layer
130 is formed using a PECVD chamber. Herein, the light-converting
layer 130 may be formed by providing the second, third and fourth
process chambers 300, 400 and 500 with a substrate temperature of
approximately 200.degree. C. to approximately 400.degree. C., a
high-frequency power of approximately 20 W to approximately 150 W
having a frequency of approximately 13.56 MHz, and a pressure of
approximately 0.5 torr to approximately 0.9 torr. For example, the
p-type amorphous silicon layer 131 may be formed to a thickness of
approximately 100 .ANG. to approximately 200 .ANG. using
B.sub.2H.sub.6 gas of 1% with respect to SiH.sub.4 gas. The i-type
amorphous silicon layer 132 may be formed to a thickness of
approximately 4000 .ANG. to approximately 5000 .ANG. using
SiH.sub.4 gas and H.sub.2 gas. The n-type amorphous silicon layer
133 may be formed to a thickness of approximately 500 .ANG. to
approximately 700 .ANG. using PH.sub.3 gas of 1% with respect to
SiH.sub.4 gas. Thereafter, a photoresist pattern 160 exposing a
predetermined region of the light-converting layer 130 is formed on
the light-converting layer 130. The photoresist pattern 160 may be
formed by forming a photoresist layer and performing an
exposure/development process on the photoresist layer by means of a
certain mask. Alternatively, the photoresist pattern 160 may be
formed performing a screen printing process. The photoresist
pattern 160 may be formed to be of a polygonal shape such as a
circular shape or tetragonal shape.
[0048] Referring to FIG. 8, in the fifth process chamber 600, the
exposed region of the light-converting layer 130 is etched to
expose the first electrode 120 using the photoresist pattern 160 as
a mask. Thus, a plurality of circular or polygonal light-converting
layers 130 are formed to be spaced apart from each other. Herein,
the etching process using the fifth process chamber 600 may be a
dry etching process performed using a capacitively coupled plasma
(CCP) dry etching device or a capacitively coupled plasma (ICP) dry
etching device. Herein, the etching gas may be obtained by mixing
one of NF.sub.3, SF.sub.6, HBr, Cl.sub.2, BCl.sub.3 and a
combination thereof with one of Ar, O.sub.2, He, N.sub.2 and a
combination thereof.
[0049] Referring to FIG. 9, an ashing process is performed to
remove the photoresist pattern 160, and then a cleaning process is
performed on the resulting structure. Thereafter, in the sixth
process chamber 700, the transparent insulating layer 140 is formed
over the entire surface of the resulting structure. For example,
the transparent insulating layer 140 is formed of an undoped ZnO
layer to a thickness of approximately 1000 .ANG. or less that can
provide the transparent insulating layer 140 with insulating
characteristics and tunneling. Also, the transparent insulating
layer 140 may be formed performing an MOCVD process.
[0050] Referring to FIG. 10, in the seventh process chamber 800, a
metal layer is formed over the entire surface of the resulting
structure. For example, the metal layer is formed of aluminum by
performing a sputtering process or a PECVD process. The metal layer
may be formed to a thickness of approximately 1000 .ANG..
Thereafter, a photolithography process using a mask for patterning
the light-converting layer 130 is performed to pattern the metal
layer, thereby forming the second electrode 150. Alternatively, a
screen printing process is performed to form a photoresist pattern
(not shown), and the photoresist pattern is used as a mask to etch
the metal layer, thereby forming the second electrode 150. Herein,
the second electrode 150 may be formed by forming a metal layer
using a metal shadow mask. Thus, the second electrode 150 having
the same pattern as the light-converting layer 130 is formed over
the transparent insulating layer 140 that is formed over the
light-converting layer 130.
[0051] It has been described that the light-converting layer 130 is
formed using the second, third and fourth process chambers 300, 400
and 500. However, the layers constituting the light-converting
layer 130 may be continuously formed by using one of the second,
third and fourth process chambers 300, 400 and 500 and controlling
process gas that flows into the process chamber. Also, if a PECVD
chamber is used as the seventh process chamber 800 in which the
metal layer is formed, the seventh process chamber 800 may be
replaced with the process chamber used to form the light-converting
layer 130.
[0052] FIG. 11 is a plan view of a solar cell in accordance with a
second embodiment of the present invention. FIG. 12 is a cutaway
perspective view of the solar cell in accordance with the second
embodiment. FIG. 13 is a cross-sectional view taken along a line
B-B' of FIG. 11. A description of an overlap between the present
embodiment of FIGS. 11 to 13 and the above-described embodiment of
FIGS. 3 to 5 will be omitted for the simplicity of explanation.
[0053] Referring to FIGS. 11 to 13, a first electrode 120 is formed
over a substrate 110, and a plurality of light-converting layers
130 are formed over the first electrode 120 in such a way that they
are spaced apart from each other. Then, a transparent insulating
layer 140 is formed over an entire surface of a resulting structure
including the light-converting layers 130, and a second electrode
150 is formed over the transparent insulating layer 140.
[0054] The substrate 110 may be a transparent substrate that is
formed of glass or transparent resin. The substrate 110 may have a
fine irregular structure formed in a surface thereof, thus
increasing the absorption of incident light.
[0055] The first electrode 120 may be formed of transparent
conductive materials such as indium tin oxide (ITO) and indium zinc
oxide (IZO). Also, the first electrode 120 may have a fine
irregular structure formed in a surface thereof.
[0056] The light-converting layer 130 is formed in plurality spaced
apart from each other. Each of the light-converting layers 130
includes the stack of the p-type amorphous silicon layer 131 that
is doped with p-type impurities, the i-type amorphous silicon layer
132 that is not doped with impurities, and the n-type amorphous
silicon layer 133 that is doped with n-type impurities.
[0057] The transparent insulating layer 140 is formed on the entire
surface of the region including the light-converting layers 130.
For example, the transparent insulating layer 140 is formed using a
ZnO layer to a thickness of approximately 1000 .ANG. or less that
can allow a tunneling operation and insulating characteristics.
[0058] The second electrode 150 is formed to cover the transparent
insulating layer 140. For example, the second electrode 150 is
formed of silver (Ag) to a thickness of approximately 500 .ANG. or
less. In this case, the second electrode 150 can transmit light
while serving as an electrode.
[0059] As described above, the solar cell in accordance with the
second embodiment includes: a plurality of first regions where the
first electrode 120, the transparent insulating layer 140, and the
second electrode 150 are stacked over the substrate 110; and a
plurality of second regions where the first electrode 120, the
light-converting layer 130, the transparent insulating layer 140,
and the second electrode 150 are stacked over the substrate 110.
The solar cell can transmit light incident from the bottom surface
of the substrate 110 through the first region, thus making it
possible to embody a transparent solar cell that can transmit
light. Herein, the distance between the first electrode 120 and the
second electrode 150 in the first region is greater than the
distance between the first electrode 120 and the second electrode
150 in the second region. Also, incident light is scattered by the
transparent insulating layer 140 and thus light is also absorbed
onto the side of the light-converting layer 130. Therefore, the
light-receiving area is not reduced, resulting in increasing the
efficiency of the solar cell.
[0060] FIGS. 14 to 17 are cross-sectional views illustrating a
method of manufacturing the solar cell in accordance with the
second embodiment. An overlapped description between the second
embodiment of FIGS. 14 to 17 and the first embodiment of FIGS. 7 to
10 will be omitted for the simplicity of explanation.
[0061] Referring to FIG. 14, transparent conductive materials such
as indium tin oxide (ITO) and indium zinc oxide (IZO) are deposited
over the transparent substrate 110 formed of glass or transparent
resin, thereby forming the first electrode 120. Herein, the
transparent substrate 110 and/or the first electrode 120 may have a
fine irregular structure formed in a surface thereof. The
light-converting layer 130, i.e., the stack of the p-type amorphous
silicon layer 131, the i-type amorphous silicon layer 132, and the
n-type amorphous silicon layer 133, is formed over the first
electrode 120. A photoresist pattern 160 exposing a predetermined
region of the light-converting layer 130 is formed on the
light-converting layer 130. The photoresist pattern 160 may be
formed to be of a polygonal shape such as a circular shape or a
tetragonal shape.
[0062] Referring to FIG. 15, the exposed region of the
light-converting layer 130 is etched to expose the first electrode
120 using the photoresist pattern 160 as a mask. Thus, a plurality
of circular or polygonal light-converting layers 130 are formed to
be spaced apart from each other. Herein, the etching process may be
a dry etching process that is performed using, e.g., a capacitively
coupled plasma (CCP) dry etching device or a capacitively coupled
plasma (ICP) dry etching device. Herein, the etching gas may be
obtained by mixing one of NF.sub.3, SF.sub.6, HBr, Cl.sub.2,
BCl.sub.3 and a combination thereof with one of Ar, O.sub.2, He,
N.sub.2 and a combination thereof.
[0063] Referring to FIG. 16, an ashing process is performed to
remove the photoresist pattern 160. Thereafter, the transparent
insulating layer 140 is formed over an entire surface of the
resulting structure. For example, the transparent insulating layer
140 is formed of an undoped ZnO layer to a thickness of
approximately 1000 .ANG. or less that can provide the transparent
insulating layer 140 with insulating characteristics and
tunneling.
[0064] Referring to FIG. 17, a sputtering process is performed to
form a metal layer, e.g., an Ag layer over an entire surface of the
resulting structure including the transparent insulating layer 140,
thereby forming the second electrode 150. For example, the Ag layer
is formed to a thickness of approximately 500 .ANG. or less that
can make the second electrode 150 transmit light while serving as
an electrode.
[0065] Although the solar cell and the method of manufacturing the
same have been described with reference to the specific
embodiments, they are not limited thereto. Therefore, it will be
readily understood by those skilled in the art that various
modifications and changes can be made thereto without departing
from the spirit and scope of the present invention defined by the
appended claims.
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