U.S. patent application number 12/458482 was filed with the patent office on 2009-11-05 for light-emitting gallium nitride-based iii-v group compound semiconductor device and manufacturing method thereof.
Invention is credited to Fen-Ren Chien, Chi-Yang Chuang, Cheng-Kuo Huang, Kuo-Chin Huang, Shyi-Ming Pan.
Application Number | 20090275156 12/458482 |
Document ID | / |
Family ID | 40095022 |
Filed Date | 2009-11-05 |
United States Patent
Application |
20090275156 |
Kind Code |
A1 |
Huang; Kuo-Chin ; et
al. |
November 5, 2009 |
Light-emitting gallium nitride-based III-V group compound
semiconductor device and manufacturing method thereof
Abstract
A light-emitting gallium nitride-based III-V group compound
semiconductor device and a manufacturing method thereof are
disclosed. The light emitting device includes a substrate, a n-type
semiconductor layer over the substrate, an active layer over the
n-type semiconductor layer, a p-type semiconductor layer over the
active layer, a conductive layer over the p-type semiconductor
layer, a first electrode disposed on the conductive layer and a
second electrode arranged on exposed part of the n-type
semiconductor layer. A resistant reflective layer or a contact
window is disposed on the p-type semiconductor layer, corresponding
to the first electrode so that current passes beside the resistant
reflective layer or by the contact window to the active layer for
generating light. When the light is transmitted to the conductive
layer for being emitted, it is not absorbed or shielded by the
first electrode. Thus the current is distributed efficiently over
the conductive layer. Therefore, both LED brightness and efficiency
are improved. Moreover, adhesion between the conductive layer and
the p-type semiconductor layer is improved so that metal peel-off
problem during manufacturing processes can be improved.
Inventors: |
Huang; Kuo-Chin; (Lung Tan,
TW) ; Pan; Shyi-Ming; (Lung Tan, TW) ; Huang;
Cheng-Kuo; (Lung Tan, TW) ; Chuang; Chi-Yang;
(Lung Tan, TW) ; Chien; Fen-Ren; (Lung Tan,
TW) |
Correspondence
Address: |
ROSENBERG, KLEIN & LEE
3458 ELLICOTT CENTER DRIVE-SUITE 101
ELLICOTT CITY
MD
21043
US
|
Family ID: |
40095022 |
Appl. No.: |
12/458482 |
Filed: |
July 14, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11979963 |
Nov 13, 2007 |
|
|
|
12458482 |
|
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Current U.S.
Class: |
438/29 ;
257/E21.09; 257/E33.067 |
Current CPC
Class: |
H01L 33/46 20130101;
H01L 33/405 20130101; H01L 33/32 20130101; H01L 33/40 20130101 |
Class at
Publication: |
438/29 ;
257/E33.067; 257/E21.09 |
International
Class: |
H01L 21/20 20060101
H01L021/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 8, 2007 |
TW |
096120865 |
Claims
1. A manufacturing method of light-emitting gallium nitride-based
III-V group compound semiconductor devices comprising the steps of:
providing a substrate; forming a n-type semiconductor layer over
the substrate; forming an active layer over the n-type
semiconductor layer; forming a p-type semiconductor layer over the
active layer; performing an etching process to expose part of the
n-type semiconductor layer; forming a resistant and reflective
layer over the p-type semiconductor layer; forming a conductive
layer over the resistant and reflective layer and the p-type
semiconductor layer; forming a first electrode that is
corresponding to the resistant and reflective layer over the
conductive layer; forming a second electrode over exposed part of
the n-type semiconductor layer.
2. The method as claimed in claim 1, wherein the resistant and
reflective layer is a dielectric reflective layer, a metal
reflective layer or combinations of them.
3. The method as claimed in claim 2, wherein the dielectric
reflective layer is made from silicon dioxide, silicon monoxide,
silicon tetranitride, nitride, amorphous semiconductor, non-crystal
semiconductor, zinc oxide, nickel oxide, titanium dioxide, oxide or
combinations of them.
4. The method as claimed in claim 2, wherein the dielectric
reflective layer is made from combinations of at least two
materials with different refractive index.
5. The method as claimed in claim 2, wherein the metal reflective
layer comprising a plurality of metal particles.
6. A manufacturing method of light-emitting gallium nitride-based
III-V group compound semiconductor devices comprising the steps of:
providing a substrate; forming a n-type semiconductor layer over
the substrate; forming an active layer over the n-type
semiconductor layer; forming a p-type semiconductor layer over the
active layer; forming a contact window on the p-type semiconductor
layer; performing an etching process to expose part of the n-type
semiconductor layer; forming a conductive layer over the contact
window and the p-type semiconductor layer; forming a first
electrode over the conductive layer and corresponding to the
contact window; and forming a second electrode over exposed part of
the n-type semiconductor layer.
7. The method as claimed in claim 6, wherein the contact window is
formed by an etching process or an ion implantation process.
8. The method as claimed in claim 6, wherein a resistant and
reflective layer is arranged over the contact window.
9. The method as claimed in claim 8, wherein the resistant and
reflective layer is a dielectric reflective layer, a metal
reflective layer or combinations of them.
10. The method as claimed in claim 9, wherein the dielectric
reflective layer is made from silicon dioxide, silicon monoxide,
silicon tetranitride, nitride, amorphous semiconductor, non-crystal
semiconductor, zinc oxide, nickel oxide, titanium dioxide, oxide or
combinations of them.
11. The method as claimed in claim 9, wherein the dielectric
reflective layer is made from combinations of at least two
materials with different refractive index.
12. The method as claimed in claim 9, wherein the metal reflective
layer comprising a plurality of metal particles.
Description
RELATED APPLICATIONS
[0001] This application is a Divisional patent application of
co-pending application Ser. No. 11/979,963, filed on 13 Nov. 2007.
The entire disclosure of the prior application, Ser. No.
11/979,963, from which an oath or declaration is supplied, is
considered a part of the disclosure of the accompanying Divisional
application and is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a light-emitting gallium
nitride-based III-V group compound semiconductor device and a
manufacturing method thereof, especially to a light-emitting
gallium nitride-based III-V group compound semiconductor device
with high resistance as well as reflection and a manufacturing
method thereof.
[0003] Now scientists in various countries are dedicated to
developing new LED material and improving the internal quantum
efficiency of LED. However, the external quantum efficiency of LED
is not improved so that there is a great difference between the
external quantum efficiency and the internal quantum efficiency of
LED. The reason that the external quantum efficiency of LED is not
improved is in that: due to distribution of current in the p-type
semiconductor layer over the active layer of the LED, photons
generated from the active layer are shielded and reflected by the
electrode over the p-type semiconductor layer and the photons also
absorbed by the substrate of the LED. Therefore, probability of
photons to be emitted from the LED is reduced.
[0004] A conventional light emitting diode includes at least a
substrate, a n-type semiconductor layer over the substrate, a light
emitting layer, and a p-type semiconductor layer, a first electrode
disposed on one side of the substrate that is opposite to the
n-type semiconductor layer and a second electrode arranged on the
p-type semiconductor layer. When a voltage is applied to the LED,
the current flows to the light emitting layer through the second
electrode and photons are generated in the light emitting layer.
Because the p-type semiconductor layer has higher resistance so
that transverse current spreading in the p-type semiconductor layer
is not easy. Thus most of current accumulate on bottom side of the
second electrode and then when the photons generated from the light
emitting layer under the second electrode are emitted from the LED,
the photons are reflected by the second electrode and further
absorbed by the substrate. Therefore, the external quantum
efficiency of the LED is dramatically reduced. Such prior art can't
meet requirements of users so that there is a need to provide a LED
with high resistance and reflection for improving light emitting
efficiency of LEDs.
SUMMARY OF THE INVENTION
[0005] Therefore it is a primary object of the present invention to
provide a light-emitting gallium nitride-based III-V group compound
semiconductor device and a manufacturing method thereof. The LED is
added with a resistant and reflective layer or is etched to form a
contact window so as to make current flows beside thereof to the
active layer for generating light. Thus when the light sent to the
conductive layer is emitted, the light is not absorbed or shielded
by the first electrode. The current is effectively spread across
the conductive layer. Therefore, the brightness and light emitting
efficiency of the LED are increased.
[0006] It is another object of the present invention to provide a
light-emitting gallium nitride-based III-V group compound
semiconductor device and a manufacturing method thereof that form a
resistant and reflective layer on the LED or have a contact window
on the p-type semiconductor layer by etching, corresponding to the
first electrode. Thus adhesion between the conductive layer and the
p-type semiconductor layer is increased so that metal peel-off
problem during manufacturing processes is improved.
[0007] In order to achieve above objects, the present invention
provides a light-emitting gallium nitride-based III-V group
compound semiconductor device and a manufacturing method thereof.
The light-emitting gallium nitride-based III-V group compound
semiconductor device includes a substrate, a n-type semiconductor
layer, an active layer, a p-type semiconductor layer, a resistant
and reflective layer, a conductive layer, a first electrode and a
second electrode. The manufacturing method consists the following
steps. Firstly, providing a substrate and then form a n-type
semiconductor layer over the substrate. Next an active layer is
formed over the n-type semiconductor layer and a p-type
semiconductor layer is formed over the active layer. Perform an
etching process on the p-type semiconductor layer, the active layer
and the n-type semiconductor layer to expose part of the n-type
semiconductor layer. Then a resistant and reflective layer is
formed over the p-type semiconductor layer while a conductive layer
is formed over the resistant and reflective layer as well as the
p-type semiconductor layer. A first electrode is arranged over the
conductive layer and the first electrode is corresponding to the
resistant and reflective layer. At last, a second electrode is
formed over the exposed part of the n-type semiconductor layer.
[0008] After applying a voltage to the LED, a current generated
passes beside the resistant and reflective layer and arrives the
active layer so as to make the active layer generate light. The
light from the active layer passes through the resistant and
reflective layer and then emits out effectively without being
shielded or absorbed by the first electrode.
[0009] Another light-emitting gallium nitride-based III-V group
compound semiconductor device of the present invention is composed
of a substrate, a n-type semiconductor layer over the substrate, an
active layer over the n-type semiconductor layer, a p-type
semiconductor layer with a contact window over the active layer, a
conductive layer over the p-type semiconductor layer with the
contact window, a first electrode disposed on the conductive layer
and corresponding to the contact window, and a second electrode
arranged on exposed part of the n-type semiconductor layer. The
manufacturing method of the light emitting device includes the
steps of providing a substrate firstly. Form the n-type
semiconductor layer over the substrate and then form the active
layer over the n-type semiconductor layer. Next form the p-type
semiconductor layer over the active layer and perform an etching
process on the p-type semiconductor layer, the active layer and the
n-type semiconductor layer so as to make part of the n-type
semiconductor layer expose. Form the conductive layer and the
contact window on the p-type semiconductor layer. The first
electrode is formed on the conductive layer and is corresponding to
the resistant and reflective layer. Finally, form the second
electrode on exposed part of the n-type semiconductor layer.
Moreover, before the conductive layer being formed over the p-type
semiconductor layer, a resistant and reflective layer is formed
over the resistant and reflective layer and is filled the contact
window.
[0010] After applying voltage to the light emitting device, the
current generated passes beside the contact window
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The structure and the technical means adopted by the present
invention to achieve the above and other objects can be best
understood by referring to the following detailed description of
the preferred embodiments and the accompanying drawings,
wherein
[0012] FIG. 1A is a schematic drawing showing structure of an
embodiment of a light emitting device according to the present
invention;
[0013] FIG. 1B is a flow chart showing a manufacturing of the light
emitting device according to the present invention;
[0014] FIG. 1C shows relationship between brightness and wavelength
of the light emitting device according to the present
invention;
[0015] FIG. 2 is a schematic drawing showing structure of another
embodiment of a light emitting device according to the present
invention;
[0016] FIG. 3A is a schematic drawing showing structure of a
further embodiment of a light emitting device according to the
present invention;
[0017] FIG. 3B is a flow chart showing a manufacturing of the light
emitting device according to the present invention;
[0018] FIG. 4 is a schematic drawing showing structure of a further
embodiment of a light emitting device according to the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0019] Refer to FIG. 1A, a light-emitting gallium nitride-based
III-V group compound semiconductor device 1 of the present
invention includes a substrate 10, a n-type semiconductor layer 11,
an active layer 13, a p-type semiconductor layer 14, a resistant
and reflective layer 15, a conductive layer 16, a first electrode
17 and a second electrode 18. Refer to FIG. 1B, a manufacturing
method of the light-emitting gallium nitride-based III-V group
compound semiconductor device of the present invention consists of
following steps:
[0020] Firstly, refer to step S10, provide a substrate 10 that is
made from one of the following material: aluminum oxide
(Al.sub.2O.sub.3), silicon carbide (SiC), gallium arsenide (GaAs),
gallium nitride (GaN), aluminum nitride (AlN), gallium phosphide
(GaP), silicon (Si), zinc oxide (ZnO), and manganese oxide (MnO),
or their combinations. Then run the step S11, form the n-type
semiconductor layer 11 over the substrate 10 and the semiconductor
layer 11 is a n-type gallium nitride semiconductor layer and is
made from aluminum nitride, gallium nitride, aluminum gallium
nitride, indium gallium nitride, aluminum indium gallium nitride
(AlInGaN) or other compounds with at least one of aluminum, indium
and gallium.
[0021] Next, run the step S12, form the active layer 13 over the
n-type semiconductor layer 11. The active layer 13 is with multiple
quantum wells and is made from aluminum nitride, gallium nitride,
aluminum gallium nitride, indium gallium nitride, aluminum indium
gallium nitride (AlInGaN) or other compounds with at least one of
aluminum, indium and gallium. Refer to the step S13, form the
p-type semiconductor layer 14 over the active layer 13 and the
p-type semiconductor layer 14 is a p-type gallium nitride
semiconductor layer and is made from aluminum nitride, gallium
nitride, aluminum gallium nitride, indium gallium nitride, aluminum
indium gallium nitride (AlInGaN) or other compounds with at least
one of aluminum, indium and gallium.
[0022] Take the step S14, perform an etching process on the p-type
semiconductor layer 14, the active layer 13, and the n-type
semiconductor layer 11 for exposing part of the n-type
semiconductor layer 11. Run the step S15, form the resistant and
reflective layer 15 over the p-type semiconductor layer 14. The
resistant and reflective layer 15 is a dielectric reflective layer
or a metal reflective layer. The dielectric reflective layer is
made from silicon dioxide, silicon monoxide, silicon tetranitride,
nitride, amorphous semiconductor, non-crystal semiconductor, zinc
oxide, nickel oxide, titanium dioxide, oxide or combinations of
them while the dielectric reflective layer can also be combinations
of at least two materials with different refractive index. The
metal reflective layer is made from Al, Ag, Pt, Ni, Cr, Pd, Sn, Au,
Zn, Ti, Pb, Ge, Cu, gold beryllium (AuBe), gold germanium (AuGe),
lead tin (PbSn), gold zinc (AuZn) or their combinations. The metal
reflective layer can also be a plurality of metal particles that
are chromium particles, nickel particles, aluminum particles,
silver particles, or titanium particles.
[0023] Then run the step S16, form the conductive layer 16 over the
resistant and reflective layer 15 and the p-type semiconductor
layer 14. The conductive layer 16 is made from Ni/Au, indium tin
oxide, cadmium tin oxide, antinomy tin oxide, conductive
transparent adhesive or their combinations. Take the step S17, form
the first electrode 17 over the conductive layer 16 and the first
electrode 17 is corresponding to the resistant and reflective layer
15. Finally, run the step S18, form the second electrode 18 over
the exposed part of the n-type semiconductor layer 11.
[0024] The present invention features on that the resistant and
reflective layer 15 is disposed on the p-type semiconductor layer
14 on the position corresponding to the first electrode 17. As to
the conventional LED, after applying a voltage to the first
electrode 17 and the second electrode 18, a current 2 is generated
and is send from the conductive layer 16 to the active layer 13 so
as to make the active layer 13 generate light. Due to higher
resistance of the p-type semiconductor layer 14, spreading of the
current 2 is difficult so that the current 2 accumulates under the
first electrode 17. When the light turns to surface of the
conductive layer 16 to emit out, it will be shielded or absorbed by
the first electrode 17. Thus light emitting efficiency of the LED
is largely reduced. In order to solve above problem, the LED 1
according to the present invention is disposed with the resistant
and reflective layer 15 so that the current 2 passes beside the
resistant and reflective layer 15 and there is no current passing
through under the resistant and reflective layer 15. The current 2
arrives the active layer 13 to generate light and the light is sent
from the active layer 13 so that the light is effectively emitted
through the resistant and reflective layer 15 without being
absorbed or shielded by the first electrode 17. Therefore,
brightness and light emitting efficiency of the LED 1 are
increased.
[0025] Refer to FIG. 1C, it shows relationship between brightness
of LED and wavelength. As shown in figure, there are two curves--a
first curve 31 and a second curve 32. The first curve 31 represents
results of LED without addition of the resistant and reflective
layer while the second curve 32 represents results of the
embodiment of the LED in FIG. 1A. It is found from the first curve
31 and the second curve 32 that brightness of the LED of the
present invention is larger than the LED without addition of the
resistant and reflective layer.
[0026] Refer to FIG. 2, another embodiment of the present invention
is disclosed. A light-emitting gallium nitride-based III-V group
compound semiconductor device 1a of the present invention is
composed of a substrate 10, a n-type semiconductor layer 11 over
the substrate 10, an active layer 13 over the n-type semiconductor
layer 11, a p-type semiconductor layer 14 over the active layer 13,
a resistant and reflective layer 15a disposed over the p-type
semiconductor layer 14, a conductive layer 16 over the p-type
semiconductor layer 14, a first electrode 17 disposed on the
conductive layer 16 and corresponding to the resistant and
reflective layer 15a, and a second electrode 18 arranged on exposed
part of the n-type semiconductor layer 11. The resistant and
reflective layer 15a of this embodiment is a dielectric reflective
layer 152a and a metal reflective layer 151a. The dielectric
reflective layer 152a is disposed over the p-type semiconductor
layer 14 while the metal reflective layer 151a is arranged over the
dielectric reflective layer 152a. Moreover, the dielectric
reflective layer 152a can also be arranged over the metal
reflective layer 151a.
[0027] Refer to FIG. 3A, a further embodiment is revealed. A
light-emitting gallium nitride-based III-V group compound
semiconductor device 1b of the present invention includes a
substrate 10, a n-type semiconductor layer 11, an active layer 13,
a p-type semiconductor layer 14b, a conductive layer 16, a first
electrode 17 and a second electrode 18. Refer to FIG. 3B, a
manufacturing method of the light-emitting gallium nitride-based
III-V group compound semiconductor device lb of the present
invention consists of following steps:
[0028] firstly, refer to step S20, take a substrate 10. Then run
the step S21, form the n-type semiconductor layer 11 over the
substrate 10. Next run the step S22, form the active layer 13 over
the n-type semiconductor layer 11. Take the step S23, form the
p-type semiconductor layer 14b on the active layer 13. The run the
step S24, perform an etching process on the p-type semiconductor
layer 14b, the active layer 13 and the n-type semiconductor layer
11 so as to make part of the n-type semiconductor layer 11 expose.
Refer to step S25, form the conductive layer 16 and a contact
window 141b on the p-type semiconductor layer 14b. The conductive
layer 16 fills the contact window 141b while the contact window
141b is formed by an etching process or an ion implantation
process. The etching process is a dry etching process, a wet
etching process or combinations of them. Then take the step S26,
form the first electrode 17 on the conductive layer 16 while the
first electrode 17 is corresponding to the contact window 141b.
Finally, run the step S27, form the second electrode 18 on exposed
part of the n-type semiconductor layer 11.
[0029] This embodiment features on that the contact window 141b is
formed on the p-type semiconductor layer 14 by the etching process
or the ion implantation process, corresponding to the first
electrode 17. Through the etching process, the contact window 141b
forms a high resistance layer. When the voltage is applied to the
first electrode 17 and the second electrode 18, a current 2
generates. While contacting with the high resistance layer formed
by the contact window 141b, the current 2 passes beside the contact
window 141b so that here is not current flowing under the contact
window 141b. Thus the current is effectively distributed over the
active layer. The current 2 is sent to the active layer 13 for
generating light and the light from the active layer 13 passes
through the resistant and reflective layer, then being radiated
without shielded and absorbed by the first electrode 17. Therefore,
both brightness and efficiency of the LED are improved
[0030] Refer to FIG. 4, a further embodiment of the present
invention is disclosed. A light-emitting gallium nitride-based
III-V group compound semiconductor device 1c of the present
invention includes a substrate 10, a n-type semiconductor layer 11
disposed over the substrate 10, an active layer 13 arranged over
the n-type semiconductor layer 11, a p-type semiconductor layer 14c
having a contact window 141c arranged over the active layer 13, a
resistant and reflective layer 15c disposed over the p-type
semiconductor layer 14c with the contact window 141c, a conductive
layer 16 arranged over the resistant and reflective layer 15c as
well as the p-type semiconductor layer 14c having a contact window
141c, a first electrode 17 disposed over the conductive layer 16
and corresponding to the resistant and reflective layer 15c, and a
second electrode 18 arranged over exposed part of the n-type
semiconductor layer 11. The resistant and reflective layer 15c of
this embodiment is a dielectric reflective layer or a metal
reflective layer and the contact window 141c of the p-type
semiconductor layer 14c is filled in with the dielectric reflective
layer or the metal reflective layer of the resistant and reflective
layer 15c.
[0031] In summary, a light-emitting gallium nitride-based III-V
group compound semiconductor device and a manufacturing method
thereof are provided by the present invention. The light-emitting
device is with high resistance and reflection so that the current
is not vertically transmitted to the active layer and is
distributed effectively over the active layer. Thus light passes
through the resistant and reflective layer to be emitted out,
without being shielded or absorbed by the first electrode.
Therefore, light-emitting efficiency and brightness are improved.
Moreover, adhesion between the conductive layer and the p-type
semiconductor layer is improved so that metal peel-off problem
during manufacturing processes can be improved.
[0032] Additional advantages and modifications will readily occur
to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific details, and
representative devices shown and described herein. Accordingly,
various modifications may be made without departing from the spirit
or scope of the general inventive concept as defined by the
appended claims and their equivalents.
* * * * *