U.S. patent application number 12/307198 was filed with the patent office on 2009-12-24 for semiconductor light emitting device.
This patent application is currently assigned to LG Innotek Co., Ltd.. Invention is credited to Sang Youl Lee.
Application Number | 20090315050 12/307198 |
Document ID | / |
Family ID | 39562657 |
Filed Date | 2009-12-24 |
United States Patent
Application |
20090315050 |
Kind Code |
A1 |
Lee; Sang Youl |
December 24, 2009 |
SEMICONDUCTOR LIGHT EMITTING DEVICE
Abstract
Disclosed is a semiconductor light emitting device. The
semiconductor light emitting device comprises a first semiconductor
layer, a second semiconductor layer, an active layer formed between
the first semiconductor layer and the second semiconductor layer, a
first reflective electrode on the first semiconductor layer to
reflect incident light, and a second reflective electrode on the
second semiconductor layer to reflect the incident light.
Inventors: |
Lee; Sang Youl; (Gwangju,
KR) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
LG Innotek Co., Ltd.
Seoul
KR
|
Family ID: |
39562657 |
Appl. No.: |
12/307198 |
Filed: |
December 17, 2007 |
PCT Filed: |
December 17, 2007 |
PCT NO: |
PCT/KR2007/006582 |
371 Date: |
December 31, 2008 |
Current U.S.
Class: |
257/98 ; 257/99;
257/E33.064; 257/E33.067 |
Current CPC
Class: |
H01L 33/42 20130101;
H01L 33/387 20130101; H01L 33/40 20130101; H01L 33/32 20130101;
H01L 33/08 20130101; H01L 33/405 20130101 |
Class at
Publication: |
257/98 ; 257/99;
257/E33.064; 257/E33.067 |
International
Class: |
H01L 33/00 20060101
H01L033/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 26, 2006 |
KR |
10-2006-0133528 |
Claims
1. A semiconductor light emitting device comprising: a first
semiconductor layer; a second semiconductor layer; an active layer
formed between the first semiconductor layer and the second
semiconductor layer; a first reflective electrode on the first
semiconductor layer to reflect incident light; and a second
reflective electrode on the second semiconductor layer to reflect
the incident light.
2. The semiconductor light emitting device as claimed in claim 1,
comprising a transparent electrode formed between the second
semiconductor layer and the second reflective electrode, and
wherein the first semiconductor layer is a n-type semiconductor
layer and the second semiconductor layer is a p-type semi-conductor
layer.
3. The semiconductor light emitting device as claimed in claim 2,
wherein the transparent electrode is formed of transparent
conductive oxide layer.
4. The semiconductor light emitting device as claimed in claim 2,
wherein the transparent electrode comprises material selected from
the group consisting of ITO, CTO, SnO.sub.2, ZnO, RuO.sub.x,
TiO.sub.x, IrO.sub.x and Ga.sub.xO.sub.y.
5. The semiconductor light emitting device as claimed in claim 1,
wherein the first reflective electrode comprises a plurality of
divided electrodes.
6. The semiconductor light emitting device as claimed in claim 5,
wherein the divided electrodes are electrically interconnected and
formed on the same plane.
7. The semiconductor light emitting device as claimed in claim 1,
wherein the first reflective electrode is formed on the first
semiconductor layer that is formed at the both sides of the second
semiconductor layer, or the first reflective electrode is formed on
the first semiconductor layer that is formed at the both sides of
the second semiconductor layer and at the divided portion of the
second semi-conductor layer.
8. The semiconductor light emitting device as claimed in claim 1,
wherein the second reflective electrode comprises a plurality of
divided electrodes.
9. The semiconductor light emitting device as claimed in claim 8,
wherein the divided electrodes are electrically interconnected.
10. The semiconductor light emitting device as claimed in claim 8,
wherein the divided electrodes are formed of `` shape.
11. The semiconductor light emitting device as claimed in claim 1,
wherein at least one of the first reflective electrode and the
second reflective electrode is formed in the form of a single layer
comprising Ag or Al, or a multi-layer comprising Ag or Al.
12. The semiconductor light emitting device as claimed in claim 1,
wherein light generated from the active layer is emitted in an
upward direction toward the first reflective electrode and the
second reflective electrode.
13. A semiconductor light emitting device comprising: a first
semiconductor layer; a second semiconductor layer; an active layer
formed between the first semiconductor layer and the second
semiconductor layer; a first electrode on the first semiconductor
layer; and a second electrode on the second semiconductor layer,
wherein at least one of the first electrode and the second
electrode is divided into a plurality of electrodes.
14. The semiconductor light emitting device as claimed in claim 13,
comprising a transparent electrode formed between the second
semiconductor layer and the second electrode, and wherein the first
semiconductor layer is a n-type semi-conductor layer and the second
semiconductor layer is a p-type semiconductor layer.
15. The semiconductor light emitting device as claimed in claim 14,
wherein the transparent electrode is formed of transparent
conductive oxide layer.
16. The semiconductor light emitting device as claimed in claim 14,
wherein the transparent electrode comprises material selected from
the group consisting of ITO, CTO, SnO.sub.2, ZnO, RuO.sub.x,
TiO.sub.x, IrO.sub.x and Ga.sub.xO.sub.y.
17. The semiconductor light emitting device as claimed in claim 13,
wherein the divided first or second electrodes are electrically
interconnected.
18. The semiconductor light emitting device as claimed in claim 13,
wherein the first electrode is divided to two or three parts, and
the second electrode is divided to two parts.
19. The semiconductor light emitting device as claimed in claim 13,
wherein the first and second electrodes are formed with reflective
electrodes that reflect incident light.
20. The semiconductor light emitting device as claimed in claim 13,
at least one of the first electrode and the second electrode is
formed in the form of a single layer comprising Ag or Al, or a
multi-layer comprising Ag or Al.
Description
TECHNICAL FIELD
[0001] The embodiment relates to a semiconductor light emitting
device.
BACKGROUND ART
[0002] A semiconductor light emitting device comprises an LED
(light emitting diode), an LD (laser diode) and the like. A
semiconductor light emitting device is used to convert electrical
signals into infrared rays, visible rays and the like by using the
characteristics of a compound semiconductor and to exchange the
converted signals.
[0003] In general, an LED has been widely used for household
electrical appliances, remote controllers, electric light boards,
indicators, and various automation devices, and is largely
classified as an IRED (infrared emitting diode) and a VLED (visible
light emitting diode).
[0004] In general, an LED having a small size is fabricated in the
form of a surface mount device so that the LED is directly mounted
on a PCB (printed circuit board). Accordingly, an LED lamp used as
a display device is also fabricated in the form of a surface mount
device. Such a surface mount device can replace an existing simple
lighting lamp and is used as a lighting indicator producing various
colors, a character indicator, an image indicator and the like.
[0005] As described above, such a semiconductor light emitting
device has been used for various fields, for example, electric
lights for daily life, electric lights for outputting rescue
signals and the like. Further, demand for a high brightness
semiconductor light emitting device has increased more and more.
Thus, a high-power light emitting device has been actively
developed.
DISCLOSURE OF INVENTION
Technical Problem
[0006] The embodiment provides a semiconductor light emitting
device capable of improving the total light emitting efficiency by
preventing light generated from an active layer from being absorbed
by electrodes.
Technical Solution
[0007] An embodiment provides a semiconductor light emitting device
comprising: a first semiconductor layer; a second semiconductor
layer; an active layer formed between the first semiconductor layer
and the second semiconductor layer; a first reflective electrode on
the first semiconductor layer to reflect incident light; and a
second reflective electrode on the second semiconductor layer to
reflect the incident light.
[0008] An embodiment provides a semiconductor light emitting device
comprising: a first semiconductor layer; a second semiconductor
layer; an active layer formed between the first semiconductor layer
and the second semiconductor layer; a first electrode on the first
semiconductor layer; and a second electrode on the second
semiconductor layer, wherein at least one of the first electrode
and the second electrode is divided into a plurality of
electrodes.
ADVANTAGEOUS EFFECTS
[0009] According to the embodiment, light generated from an active
layer is prevented from being absorbed by electrodes, so that the
total light emitting efficiency can be improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a sectional view schematically showing the stack
structure of a semi-conductor light emitting device according to a
first embodiment;
[0011] FIG. 2 is a sectional view schematically showing the stack
structure of a semi-conductor light emitting device according to a
second embodiment;
[0012] FIG. 3 is a sectional view schematically showing the stack
structure of a semi-conductor light emitting device according to a
third embodiment;
[0013] FIG. 4 is a sectional view schematically showing the stack
structure of a semi-conductor light emitting device according to a
fourth embodiment; and
[0014] FIG. 5 is a sectional view schematically showing the stack
structure of a semi-conductor light emitting device according to a
fifth embodiment.
MODE FOR THE INVENTION
[0015] In the description of an embodiment, it will be understood
that, when a layer (or film), a region, a pattern, or a structure
is referred to as being "on" or "under" another substrate, another
layer (or film), another region, another pad, or another pattern,
it can be "directly" or "indirectly" on the other substrate, layer
(or film), region, pad, or pattern, or one or more intervening
layers may also be present.
[0016] Hereinafter, embodiments will be described with reference to
the accompanying drawings.
[0017] FIG. 1 is a sectional view schematically showing the stack
structure of a semi-conductor light emitting device according to a
first embodiment.
[0018] As shown in FIG. 1, the semiconductor light emitting device
100 according to the first embodiment comprises a substrate 110, a
buffer layer 120, a first semiconductor layer for example, an
n-type semiconductor layer 130, an active layer 140, a second
semiconductor layer for example, a p-type semiconductor layer 150,
a transparent electrode 160, a first reflective electrode for
example, an n-type reflective electrode 170, and a second
reflective electrode for example, a p-type reflective electrode
180.
[0019] First, the substrate 110 is formed of one selected from the
group consisting of Al.sub.2O.sub.3, Si, SiC, GaAs, ZnO, MgO or a
compound thereof.
[0020] The buffer layer 120 may have a stack structure such as
AlInN/GaN, In.sub.xGa.sub.1-xN/GaN,
Al.sub.xIn.sub.yGa.sub.1-x-yN/In.sub.xGa.sub.1-xN/GaN and the
like.
[0021] The n-type semiconductor layer 130 and the p-type
semiconductor layer 150 may comprise nitride semiconductor layers,
respectively.
[0022] The active layer 140 is formed between the n-type
semiconductor layer 130 and the p-type semiconductor layer 150. The
active layer 140 may have a single quantum well structure or a
multi-quantum well structure.
[0023] The transparent electrode 160 is formed on the p-type
semiconductor layer 150. The transparent electrode 160 comprises
materials that have superior light transmittance and increase
diffusion of electric current. The transparent electrode 160 may be
formed of transparent conductive oxide layer, such as ITO, CTO,
SnO.sub.2, ZnO, RuO.sub.x, TiO.sub.x, IrO.sub.x or
Ga.sub.xO.sub.y.
[0024] The p-type reflective electrode 180 is formed on the
transparent electrode 160, and the n-type reflective electrode 170
is formed on the n-type semiconductor layer 130.
[0025] The p-type reflective electrode 180 and the n-type
reflective electrode 170 comprise metal containing reflective
material to serve as a bonding pad. The p-type reflective electrode
180 and the n-type reflective electrode 170 comprise reflective
material such as Ag or Al to have a single layer structure or a
multi-layer structure.
[0026] Further, the transparent electrode 160 and the n-type
reflective electrode 170 serve as an ohmic contact layer.
[0027] For example, the n-type reflective electrode 170 can be
formed with an ohmic contact layer by using reflective material
such as Al. Further, the n-type reflective electrode 170 can be
formed with an ohmic contact layer by using Ti, Cr and the like.
Furthermore, the n-type reflective electrode 170 may have a
thickness less than several nm in order to increase the
reflectivity of a reflective layer.
[0028] Further, the transparent electrode 160 is located below the
p-type reflective electrode 180. The transparent electrode 160
serves as an ohmic contact layer. Accordingly, the p-type
reflective electrode 180 can serve as a reflective layer. In
addition, the p-type reflective electrode 180 can be prepared in
the form of a bonding pad, in which an ohmic contact layer is
formed by Ti or Cr having a thickness less than several nm and a
reflective layer is additionally formed.
[0029] According to the semiconductor light emitting device 100 of
the first embodiment as described above, the n-type and p-type
reflective electrodes 170 and 180 are provided thereto, so that the
light generated from the active layer 140 can be prevented from
being absorbed by the n-type and p-type reflective electrodes 170
and 180. The light generated from the active layer 140 is reflected
from the side or bottom surfaces of the n-type and p-type
reflective electrodes 170 and 180 instead of being absorbed by the
n-type and p-type reflective electrodes 170 and 180.
[0030] Accordingly, the semiconductor light emitting device 100 of
the first embodiment can improve the brightness thereof. Further,
the semiconductor light emitting device 100 of the first embodiment
can be applied to a low-power semiconductor light emitting device
as well as a high-power semiconductor light emitting device.
[0031] Meanwhile, the embodiment proposes a scheme for dividing a
reflective electrode in order to further improve the brightness of
the semiconductor light emitting device. FIGS. 2 to 5 show an
example of the semiconductor light emitting device comprising
divided reflective electrodes.
[0032] As shown in FIGS. 2 to 5, when dividing a reflective
electrode, either an n-type reflective electrode or a p-type
reflective electrode can be divided, or both the n-type reflective
electrode and the p-type reflective electrode can also be divided.
Further, the divided n-type reflective electrodes are electrically
interconnected, and the divided p-type reflective electrodes are
also electrically interconnected. For example, the divided n-type
reflective electrodes can be patterned on the same plane and the
divided p-type reflective electrodes can also be patterned on the
same plane.
[0033] FIG. 2 is a sectional view schematically showing the stack
structure of a semi-conductor light emitting device according to a
second embodiment.
[0034] As shown in FIG. 2, the semiconductor light emitting device
200 according to the second embodiment comprises a substrate 210, a
buffer layer 220, an n-type semi-conductor layer 230, an active
layer 240, a p-type semiconductor layer 250, a transparent
electrode 260, p-type reflective electrodes 280 and 285, and n-type
reflective electrodes 270, 272 and 274.
[0035] According to the semiconductor light emitting device 200 of
the second embodiment, two p-type reflective electrodes 280 and 285
and three n-type reflective electrodes 270, 272 and 274 are
formed.
[0036] The two p-type reflective electrodes 280 and 285 formed
through division are electrically interconnected. According to one
example, the two p-type reflective electrodes 280 and 285 can be
patterned on the same plane in the form of a substantial ``
shape.
[0037] Further, the three n-type reflective electrodes 270, 272 and
274 formed through division are electrically interconnected. The
three n-type reflective electrodes 270, 272 and 274 can be
patterned on the same plane.
[0038] The two p-type reflective electrodes 280 and 285 are formed
on the transparent electrode 260, and the three n-type reflective
electrodes 270, 272 and 274 are formed on the n-type semiconductor
layer 230.
[0039] As described above, the two p-type reflective electrodes 280
and 285 and the three n-type reflective electrodes 270, 272 and 274
are formed through division, so that various light paths can be
ensured even when an area, in which the reflective electrodes are
formed in the second embodiment, is equal to that in which the
reflective electrodes are formed in the first embodiment.
Accordingly, the light generated from the active layer 240 can be
more efficiently emitted to the upward direction. As a result, the
brightness of the semiconductor light emitting device comprising
the divided reflective electrodes can be increased more and
more.
[0040] The second embodiment shows an example in which the
electrodes formed through division are reflective electrodes.
However, the electrodes formed through division may be typical
electrodes, other than the reflective electrodes, which are applied
to fields related to a semiconductor light emitting device.
[0041] FIG. 3 is a sectional view schematically showing the stack
structure of a semi-conductor light emitting device according to a
third embodiment.
[0042] As shown in FIG. 3, the semiconductor light emitting device
300 according to the third embodiment comprises a substrate 310, a
buffer layer 320, an n-type semi-conductor layer 330, an active
layer 340, a p-type semiconductor layer 350, a transparent
electrode 360, p-type reflective electrodes 380 and 385, and an
n-type reflective electrode 370.
[0043] According to the semiconductor light emitting device 300 of
the third embodiment, two p-type reflective electrodes 380 and 385
and one n-type reflective electrode 370 are formed.
[0044] The two p-type reflective electrodes 380 and 385 formed
through division are electrically interconnected. According to one
example, the two p-type reflective electrodes 380 and 385 can be
patterned on the same plane in the form of a substantial ``
shape.
[0045] The two p-type reflective electrodes 380 and 385 are formed
on the transparent electrode 360, and the one n-type reflective
electrode 370 is formed on the n-type semiconductor layer 330.
[0046] As described above, the two p-type reflective electrodes 380
and 385 are formed through division, so that various light paths
can be ensured and the light generated from the active layer 340
can be more efficiently emitted to the upward direction.
Accordingly, the brightness of the semiconductor light emitting
device comprising the divided reflective electrodes can be
increased more and more.
[0047] The third embodiment shows an example in which the
electrodes formed through division are reflective electrodes.
However, the electrodes formed through division may be typical
electrodes, other than the reflective electrodes, which are applied
to fields related to a semiconductor light emitting device.
[0048] FIG. 4 is a sectional view schematically showing the stack
structure of a semi-conductor light emitting device according to a
fourth embodiment.
[0049] As shown in FIG. 4, the semiconductor light emitting device
400 according to the fourth embodiment comprises a substrate 410, a
buffer layer 420, an n-type semi-conductor layer 430, an active
layer 440, a p-type semiconductor layer 450, a transparent
electrode 460, p-type reflective electrodes 480 and 485, and n-type
reflective electrodes 470 and 475.
[0050] According to the semiconductor light emitting device 400 of
the fourth embodiment, two p-type reflective electrodes 480 and 485
and two n-type reflective electrodes 470 and 475 are formed.
[0051] The two p-type reflective electrodes 480 and 485 formed
through division are electrically interconnected. According to one
example, the two p-type reflective electrodes 480 and 485 can be
patterned on the same plane in the form of a substantial ``
shape.
[0052] The two n-type reflective electrodes 470 and 475 formed
through division are electrically interconnected. The two n-type
reflective electrodes 470 and 475 can be patterned on the same
plane in the form of a substantial `` shape.
[0053] The two p-type reflective electrodes 480 and 485 are formed
on the transparent electrode 460, and the two n-type reflective
electrodes 470 and 475 are formed on the n-type semiconductor layer
430.
[0054] As described above, the two p-type reflective electrodes 480
and 485 and the two n-type reflective electrodes 470 and 475 are
formed through division, so that various light paths can be ensured
and the light generated from the active layer 440 can be more
efficiently emitted to the upward direction. Accordingly, the
brightness of the semiconductor light emitting device comprising
the divided reflective electrodes can be increased more and
more.
[0055] The fourth embodiment shows an example in which the
electrodes formed through division are reflective electrodes.
However, the electrodes formed through division may also comprise
typical electrodes, other than the reflective electrodes, which are
applied to fields related to a semiconductor light emitting
device.
[0056] FIG. 5 is a sectional view schematically showing the stack
structure of a semi-conductor light emitting device according to a
fifth embodiment.
[0057] As shown in FIG. 5, the semiconductor light emitting device
500 according to the fifth embodiment comprises a substrate 510, a
buffer layer 520, an n-type semi-conductor layer 530, an active
layer 540, a p-type semiconductor layer 550, a transparent
electrode 560, p-type reflective electrodes 580 and 585, and n-type
reflective electrodes 570 and 572.
[0058] According to the semiconductor light emitting device 500 of
the fifth embodiment, two p-type reflective electrodes 580 and 585
and two n-type reflective electrodes 570 and 572 are formed.
[0059] The two p-type reflective electrodes 580 and 585 formed
through division are electrically interconnected. According to one
example, the two p-type reflective electrodes 580 and 585 can be
patterned on the same plane in the form of a substantial ``
shape.
[0060] The two n-type reflective electrodes 570 and 572 formed
through division are electrically interconnected. The two n-type
reflective electrodes 570 and 572 can be patterned on the same
plane in the form of a substantial `` shape.
[0061] The two p-type reflective electrodes 580 and 585 are formed
on the transparent electrode 560, and the two n-type reflective
electrodes 570 and 572 are adjacently formed on the n-type
semiconductor layer 530.
[0062] As described above, the two p-type reflective electrodes 580
and 585 and the two n-type reflective electrodes 570 and 572 are
formed through division, so that various light paths can be ensured
and the light generated from the active layer 540 can be more
efficiently emitted to the upward direction. Accordingly, the
brightness of the semiconductor light emitting device comprising
the divided reflective electrodes can be increased more and
more.
[0063] The fifth embodiment shows an example in which the
electrodes formed through division are reflective electrodes.
However, the electrodes formed through division may be typical
electrodes, other than the reflective electrodes, which are applied
to fields related to a semiconductor light emitting device.
[0064] According to the embodiments as described above, the number
of the reflective electrodes formed through division is two or
three. However, the number of the reflective electrodes formed
through division can be varied according to the design thereof.
[0065] Further, the embodiments show an example of the P-N junction
semiconductor light emitting device in which the p-type
semiconductor layer is formed on the n-type semi-conductor layer.
However, the embodiment can be applied to an N-P-N junction
semi-conductor light emitting device in which an n-type
semiconductor layer is additionally formed on the p-type
semiconductor layer. The N-P-N junction semiconductor light
emitting device denotes a semiconductor light emitting device in
which both first and second electrode layers are provided as n-type
semiconductor layers, and a p-type semiconductor layer is formed
between the n-type semiconductor layers. At this time, a first
electrode is formed on the first electrode layer, which is the
n-type semiconductor layer, while making contact with the first
electrode layer. A second electrode is formed on the second
electrode layer, which is the n-type semiconductor layer, while
making contact with the second electrode layer.
[0066] Any reference in this specification to "one embodiment", "an
embodiment", "example embodiment", etc., means that a particular
feature, structure, or characteristic described in connection with
the embodiment is included in at least one embodiment of the
invention. The appearances of such phrases in various places in the
specification are not necessarily all referring to the same
embodiment. Further, when a particular feature, structure, or
characteristic is described in connection with any embodiment, it
is submitted that it is within the purview of one skilled in the
art to effect such feature, structure, or characteristic in
connection with other ones of the embodiments.
[0067] Although embodiments have been described with reference to a
number of illustrative embodiments thereof, it should be understood
that numerous other modifications and embodiments can be devised by
those skilled in the art that will fall within the spirit and scope
of the principles of this disclosure. More particularly, various
variations and modifications are possible in the component parts
and/or arrangements of the subject combination arrangement within
the scope of the disclosure, the drawings and the appended claims.
In addition to variations and modifications in the component parts
and/or arrangements, alternative uses will also be apparent to
those skilled in the art.
INDUSTRIAL APPLICABILITY
[0068] According to the embodiments as described above, the
semiconductor light emitting device comprises a plurality of
divided reflective electrodes as electrodes, so that the light
generated from the active layer can be transmitted in the upward
direction through gaps between the electrodes or reflected from the
electrodes instead of being absorbed by the electrodes.
Consequently, the total light emitting efficiency of the
semiconductor light emitting device can be improved.
* * * * *