U.S. patent application number 13/595682 was filed with the patent office on 2012-12-20 for light emitting device and method of fabricating the same.
Invention is credited to Dae Sung KANG, Hyo Kun Son.
Application Number | 20120319130 13/595682 |
Document ID | / |
Family ID | 40135537 |
Filed Date | 2012-12-20 |
United States Patent
Application |
20120319130 |
Kind Code |
A1 |
KANG; Dae Sung ; et
al. |
December 20, 2012 |
LIGHT EMITTING DEVICE AND METHOD OF FABRICATING THE SAME
Abstract
Provided are a light emitting device and a method of fabricating
the same. The light emitting device comprises: a first conductive
semiconductor layer; an active layer comprising an InGaN well layer
and a GaN barrier layer on the first conductive semiconductor
layer; and a second conductive semiconductor layer on the active
layer. The GaN barrier layer comprises an AlGaN layer.
Inventors: |
KANG; Dae Sung; (Gwangju,
KR) ; Son; Hyo Kun; (Gwangju, KR) |
Family ID: |
40135537 |
Appl. No.: |
13/595682 |
Filed: |
August 27, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12145320 |
Jun 24, 2008 |
8257993 |
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13595682 |
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Current U.S.
Class: |
257/76 ;
257/E33.023 |
Current CPC
Class: |
H01L 33/32 20130101;
H01L 33/06 20130101 |
Class at
Publication: |
257/76 ;
257/E33.023 |
International
Class: |
H01L 33/32 20100101
H01L033/32 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 25, 2007 |
KR |
10-2007-0062005 |
Claims
1. A light emitting device comprising: a first conductive
semiconductor layer; an active layer on the first conductive
semiconductor layer; and a second conductive semiconductor layer on
the active layer, wherein the active layer comprises a plurality of
structures including an InGaN well layer, a first GaN barrier layer
on the InGaN well layer, an AlGaN layer on the first GaN barrier
layer, and a second GaN barrier layer on the AlGaN layer, and
wherein the second GaN barrier layer has less pits than the first
GaN barrier layer thereof.
2. The light emitting device according to claim 1, wherein the
AlGaN layer is directly inter disposed between the first GaN
barrier layer and the second GaN barrier layer.
3. The light emitting device according to claim 1, wherein the
AlGaN layer is thicker than the first GaN barrier layer.
4. The light emitting device according to claim 1, wherein the
AlGaN layer is thicker than the second GaN barrier layer.
5. The light emitting device according to claim 1, wherein the
AlGaN layer is thicker than both the first GaN barrier layer and
the second GaN barrier layer.
6. The light emitting device according to claim 1, wherein each of
the plurality of structures has sequentially and directly stacked
the InGaN well layer, the first GaN barrier layer, the AlGaN layer,
and the second GaN barrier layer.
7. The light emitting device according to claim 1, wherein the
AlGaN layer is formed with a thickness of 5.18 .ANG. to 15.54
.ANG..
8. The light emitting device according to claim 1, wherein the
AlGaN layer has a thickness of one to three mono layers.
9. The light emitting device according to claim 1, wherein the
AlGaN layer is expressed as Al.sub.xGa.sub.1-xN
(0.1.ltoreq..times..ltoreq.0.5).
10. The light emitting device according to claim 1, wherein the
AlGaN layer is formed in the GaN barrier layer, and a top and a
bottom of the AlGaN layer directly contact the second and first
portions of the GaN barrier layer, respectively.
11. The light emitting device according to claim 1, wherein the
AlGaN layer is formed by directly contacting the first GaN barrier
layer.
12. The light emitting device according to claim 1, wherein the
second GaN barrier layer is formed by directly contacting the AlGaN
layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a 37 C.F.R. .sctn.1.53(b)
continuation of co-pending U.S. patent application Ser. No.
12/145,320 filed Jun. 24, 2008, which claims priority on Korean
Patent Application No. 10-2007-0062005, filed on Jun. 25, 2007. The
entire contents of all of the above applications are hereby
incorporated by reference.
BACKGROUND
[0002] Embodiments relate to a light emitting device and a method
of fabricating the same.
[0003] A light emitting diode is generally used as a light emitting
device.
[0004] In the light emitting diode, an N-type semiconductor layer,
an active layer, and a P-type semiconductor layer are stacked.
Thus, light is generated in the active layer and then is emitted to
the outside according to applied power supply.
SUMMARY
[0005] Embodiments provide a light emitting device and a method of
fabricating the same.
[0006] Embodiments also provide a light emitting device with
improved light emitting efficiency and electrical characteristic
and a method of fabricating the same.
[0007] In an embodiment, a light emitting device comprises: a first
conductive semiconductor layer; an active layer on the first
conductive semiconductor layer; and a second conductive
semiconductor layer on the active layer. The active layer comprises
an InGaN well layer, a first GaN barrier layer on the InGaN well
layer, an AlGaN layer on the first GaN barrier layer, and a second
GaN barrier layer on the AlGaN layer.
[0008] In an embodiment, a light emitting device comprises: a first
conductive semiconductor layer; an active layer comprising an InGaN
well layer and a GaN barrier layer on the first conductive
semiconductor layer; and a second conductive semiconductor layer on
the active layer. The GaN barrier layer comprises an AlGaN
layer.
[0009] In an embodiment, a method of fabricating a light emitting
device comprises: forming a first conductive semiconductor layer;
forming an active layer on the first conductive semiconductor
layer; and forming a second conductive semiconductor layer on the
active layer. The forming of the active layer comprises: forming an
InGaN well layer on the first conductive semiconductor layer;
forming a first GaN barrier layer on the InGaN well layer; forming
an AlGaN layer on the first GaN barrier layer; and forming a second
GaN barrier layer on the AlGaN layer.
[0010] The details of one or more embodiments are set forth in the
accompanying drawings and the description below. Other features
will be apparent from the description and drawings, and from the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a cross-sectional view of a light emitting device
according to a first embodiment.
[0012] FIG. 2 is a cross-sectional view of a light emitting device
according to a second embodiment.
[0013] FIGS. 3 to 8 are cross-sectional views illustrating a method
of fabricating a light emitting device according to an
embodiment.
[0014] FIG. 9 is a graph illustrating temperature change and
injection gas during the forming of an active layer in a method of
fabricating a light emitting device according to an embodiment.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0015] In the following description, it will be understood that
when a layer (or film) is referred to as being `on/under` another
layer or substrate, it can be directly on/under the another layer
or substrate, or intervening layers may also be present.
[0016] Hereinafter, a light emitting device and a method of
fabricating the same will be described with reference to the
accompanying drawings.
[0017] FIG. 1 is a cross-sectional view of a light emitting device
according to a first embodiment.
[0018] Referring to FIG. 1, the light emitting device of the
present invention includes a substrate 10, a buffer layer 20 formed
on the substrate 10, an un-doped GaN layer 30 formed on the buffer
layer 20, a first conductive semiconductor layer 40 formed on the
un-doped GaN layer 30, an active layer 50 formed on the first
conductive semiconductor layer 40, a second conductive
semiconductor layer 60 formed on the active layer 50, and a first
electrode layer 70 and a second electrode layer 80 formed on the
first conductive semiconductor layer 40 and the second conductive
semiconductor layer 60, respectively.
[0019] Additionally, the active layer 50 includes an InGaN well
layer 51, a first GaN barrier layer 52 formed on the InGaN well
layer 51, an AlGaN layer 53 formed on the first GaN barrier layer
52, and a second GaN barrier layer 54 formed on the AlGaN layer
53.
[0020] The AlGaN layer 53 may grow with a thickness of one to three
mono layers. That is, the AlGaN layer 53 may grow with a thickness
of 5.18 .ANG. to 15.54 .ANG..
[0021] In the light emitting device of the first embodiment, the
active layer 50 is used for preventing a leakage current and
forming a high quality barrier layer through the AlGaN layer 53
between the first GaN barrier layer 52 and the second GaN barrier
layer 54.
[0022] Especially, the second GaN barrier layer 54 is formed at a
temperature of 850.degree. C. to 1100.degree. C., which is higher
than a temperature at which the first GaN barrier layer 52 is
formed.
[0023] Accordingly, the second GaN barrier layer 54 may be formed
of a high quality thin layer and a pit causing a leakage current
may be removed, such that electrical characteristics can be
improved.
[0024] FIG. 2 is a cross-sectional view of a light emitting device
according to a second embodiment.
[0025] Referring to FIG. 2, only the different contents between
FIG. 2 and FIG. 1 will be described.
[0026] In the light limiting device of the second embodiment, an
active layer 50 includes an InGaN well layer 51, a first GaN
barrier layer 52 formed on the InGaN well layer 51, an AlGaN layer
53 formed on the first GaN barrier layer 52, and a second GaN
barrier layer 54 formed on the AlGaN layer 53, all of which
constitute one period.
[0027] Moreover, the active layer 50 includes an InGaN well layer
55 formed on the second GaN barrier layer 54, a first GaN barrier
layer 56 formed on the InGaN well layer 55, an AlGaN layer 57
formed on the first GaN barrier layer 56, and a second GaN barrier
layer 58 formed on the AlGaN layer 57, all of which constitute
another period.
[0028] Although not illustrated, the active layer 50 includes a
plurality of periods, such that a plurality of well layers, first
barrier layers, AlGaN layers, and second barrier layers can be
repeatedly formed.
[0029] That is, the active layer 50 may have a multi quantum well
structure.
[0030] FIGS. 3 to 8 are cross-sectional views illustrating a method
of fabricating a light emitting device according to an
embodiment.
[0031] Referring to FIG. 3, a substrate 10 is prepared, and then a
buffer layer 20, an un-doped GaN layer 30, a first conductive
semiconductor layer 40, and an InGaN well layer 51 are sequentially
formed on the substrate 10.
[0032] The substrate 10 may be formed of at least one of sapphire
(Al2O3), Si, SiC, GaAs, ZnO, or MgO, and the buffer layer 20 may be
formed of at least one of an AlInN/GaN multilayer structure, an
InxGa1-xN/GaN multilayer structure, or an
AlxInyGa1-(x+y)N/InxGa1-xN/GaN multilayer structure.
[0033] The un-doped GaN layer 30 is formed with a supply of TMGa
and NH3. At this point, N2 and H2 may be used as a purge gas and a
carrier gas.
[0034] The first conductive semiconductor layer 40 may be formed of
a Si--In co-doped GaN layer doped with silicon and indium
simultaneously, and is an N-type semiconductor layer.
[0035] The InGaN well layer 51 is formed with a supply of NH3,
TMGa, and TMIn at a temperature of 650.degree. C. to 850.degree. C.
In the embodiment of FIG. 9, the InGaN well layer 51 is formed at a
temperature of 700.degree. C.
[0036] Referring to FIG. 4, the first GaN barrier layer 52 is
formed on the InGaN well layer 51.
[0037] After the forming the InGaN well layer 51, the first GaN
barrier layer 52 is formed with a supply of NH3 and TMGa at a
temperature of 800.degree. C. to 1000.degree. C. by drastically
increasing a temperature by 150.degree. C. with a ratio of
2.degree. C./sec. In the embodiment of FIG. 9, the first GaN
barrier layer 52 is formed by increasing temperature from
700.degree. C. to 850.degree. C.
[0038] Referring to FIG. 5, an AlGaN layer 53 is formed on the
first GaN barrier layer 52.
[0039] The AlGaN layer 53 is formed with a supply of NH3, TMGa, and
TMAl at a temperature of 800.degree. C. to 1000.degree. C. The
AlGaN layer 53 may grow with a thickness of 5.18 .ANG. to 15.54
.ANG.. In the embodiment of FIG. 9, the AlGaN layer 53 is formed at
a temperature of 850 .ANG..
[0040] Referring to FIG. 6, a second GaN barrier layer 54 is formed
on the AlGaN layer 53.
[0041] After the forming the AlGaN layer 53, the second GaN barrier
layer 54 is formed with a supply of NH3 and TMGa at a temperature
of 850.degree. C. to 1100.degree. C. by drastically increasing
temperature by about 150.degree. C. at a ratio of 2.degree. C./sec.
In an embodiment of FIG. 9, the second GaN barrier layer 54 is
formed by increasing temperature from 850.degree. C. to
1000.degree. C.
[0042] The AlGaN layer 53 has durability against high temperature.
Accordingly, the second GaN barrier layer 54 can be formed at a
temperature that is higher than a temperature at which the first
GaN barrier layer 52 is formed. Accordingly, the quality of the
second GaN barrier layer 54 can be improved such that pits (which
may be formed on the second GaN barrier layer 54) are
decreases.
[0043] The AlGaN layer 53 includes Al of 10% to 50%. That is, the
AlGaN layer 53 may be expressed as AlxGa1-xN
(0.1.ltoreq..times..ltoreq.0.5).
[0044] On the other hand, the NH3 and TMGa are continuously
supplied to protect the surface of the InGaN well layer 51 during
the forming of an active layer 50 of FIG. 7.
[0045] Referring to FIG. 7, a second conductive semiconductor layer
60 is formed on the second GaN barrier layer 54.
[0046] The second conductive semiconductor layer 60 may be formed
of a GaN layer doped with Mg, and is a P-type semiconductor
layer.
[0047] Referring to FIG. 8, the second conductive semiconductor
layer 60, the active layer 50, and the first conductive
semiconductor layer 40 are partially removed.
[0048] Furthermore, a first electrode layer 70 is formed on the
first conductive semiconductor layer 40, and a second electrode
layer 80 is formed on the second conductive semiconductor layer
60.
[0049] In the above light emitting device, the active layer emits
light when power supply is applied to the first electrode layer 70
and the second electrode layer 80.
[0050] On the other hand, the light emitting device of the
embodiment includes the active layer 50 having a structure of the
InGaN well layer 51, the first GaN barrier layer 52, the AlGaN
layer 53, and the second GAN barrier layer 54. Additionally, since
the quality of the second GaN barrier layer is excellent,
electrostatic discharge (ESD) and breakdown voltage characteristics
are outstanding.
[0051] Embodiments provide a light emitting device and a method of
fabricating the same. Furthermore, provided is a light emitting
device with improved light emitting efficiency and electrical
characteristics and a method of fabricating the same.
[0052] Although a lateral type light emitting device (in which two
electrodes are arranged in the top direction of a semiconductor
layer) is described in the above embodiments, the embodiments may
be applied to a vertical type light emitting device (in which two
electrodes are disposed at the top and bottom directions of a
semiconductor layer).
[0053] 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.
[0054] 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.
* * * * *