U.S. patent application number 12/678103 was filed with the patent office on 2012-05-03 for light emitting device and method for manufacturing the same.
Invention is credited to Dae Sung Kang.
Application Number | 20120104434 12/678103 |
Document ID | / |
Family ID | 41265186 |
Filed Date | 2012-05-03 |
United States Patent
Application |
20120104434 |
Kind Code |
A1 |
Kang; Dae Sung |
May 3, 2012 |
LIGHT EMITTING DEVICE AND METHOD FOR MANUFACTURING THE SAME
Abstract
Provided are a light emitting device and a method for
manufacturing the same. The light emitting device comprises a first
conductive type semiconductor layer, an active layer, a second
conductive type semiconductor layer, and a light extraction layer.
The active layer is formed on the first conductive type
semiconductor layer. The second conductive type semiconductor layer
is formed on the active layer. The light extraction layer is formed
on the second conductive type semiconductor layer. The light
extraction layer has a refractive index smaller than or equal to a
refractive index of the second conductive type semiconductor
layer.
Inventors: |
Kang; Dae Sung; (Gwangju,
KR) |
Family ID: |
41265186 |
Appl. No.: |
12/678103 |
Filed: |
May 8, 2009 |
PCT Filed: |
May 8, 2009 |
PCT NO: |
PCT/KR2009/002448 |
371 Date: |
March 12, 2010 |
Current U.S.
Class: |
257/98 ;
257/E33.068 |
Current CPC
Class: |
H01L 33/24 20130101;
H01L 33/32 20130101; H01L 33/38 20130101; H01L 33/06 20130101; H01L
33/20 20130101; H01L 33/02 20130101; H01L 33/36 20130101 |
Class at
Publication: |
257/98 ;
257/E33.068 |
International
Class: |
H01L 33/30 20100101
H01L033/30 |
Foreign Application Data
Date |
Code |
Application Number |
May 8, 2008 |
KR |
10-2008-0042973 |
Claims
1-15. (canceled)
16. A light emitting device comprising: a first conductive type
semiconductor layer; an active layer on the first conductive type
semiconductor layer; a second conductive type semiconductor layer
on the active layer; and a light extracting layer on the second
conductive type semiconductor layer, wherein the light extracting
layer is formed on a peripheral portion of the second conductive
type semiconductor layer.
17. The light emitting device of claim 16, wherein the light
extracting layer has a refractive index equal to or smaller than a
refractive index of the second conductive type semiconductor
layer.
18. The light emitting device of claim 16, wherein the light
extracting layer has a chemical formula of
Al.sub.xGa.sub.1-xN.sub.y (0.ltoreq.x.ltoreq.1).
19. The light emitting device of claim 16, wherein the light
extracting layer is formed along an edge of the second conductive
type semiconductor layer while surrounding the second conductive
type semiconductor layer.
20. The light emitting device of claim 16, wherein the light
extracting layer is formed at a side thereof with an inclined
surface.
21. The light emitting device of claim 20, wherein the inclined
surface has an inclination angle of 58.degree. to 63.degree. with
respect to a top surface of the second conductive type
semiconductor layer.
22. The light emitting device of claim 16, wherein the second
conductive type semiconductor layer, the active layer and the first
conductive type semiconductor layer are selectively etched such
that a part of the first conductive type semiconductor layer is
exposed upward and a first electrode layer is formed on the first
conductive type semiconductor layer exposed upward.
23. The light emitting device of claim 16, wherein the light
extracting layer, the second conductive type semiconductor layer,
the active layer and the first conductive type semiconductor layer
are selectively etched such that a part of the first conductive
type semiconductor layer is exposed in upward and lateral
directions and a first electrode layer is formed on the first
conductive type semiconductor layer exposed in the upward and
lateral directions.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a light emitting device
and a method for manufacturing the same.
BACKGROUND ART
[0002] Recently, studies are being actively conducted on a Light
Emitting Diode (LED) as a light emitting device.
[0003] LED includes a first conductive type semiconductor layer, an
active layer, and a second conductive type semiconductor layer.
Light is generated by combination of electrons and holes in the
active layer when power is applied to the first conductive type
semiconductor layer and the second conductive type semiconductor
layer.
[0004] LEDs are used for various machines and electrical and
electronic devices such as display devices, lighting devices,
mobile communication terminals, and automobiles.
DISCLOSURE OF THE INVENTION
Technical Problem
[0005] Embodiments provide a light emitting device and a method for
manufacturing the same.
[0006] Embodiments provide a light emitting device and a method for
manufacturing the same, which has improved light extraction
efficiency.
Technical Solution
[0007] In one embodiment, a light emitting device comprises: a
first conductive type semiconductor layer; an active layer on the
first conductive type semiconductor layer; a second conductive type
semiconductor layer on the active layer; and a light extraction
layer on the second conductive type semiconductor layer, the light
extraction layer having a refractive index smaller than or equal to
a refractive index of the second conductive type semiconductor
layer.
[0008] In another embodiment, a method for manufacturing a light
emitting device comprises: forming a first conductive type
semiconductor layer, an active layer, and a second conductive type
semiconductor layer; forming a selectively patterned mask layer on
the second conductive type semiconductor layer; forming a light
extraction layer on the second conductive type semiconductor layer
on which the mask layer is not formed and removing the mask layer;
performing a scribing process around the light extraction layer;
and selectively etching the second conductive type semiconductor
layer, the active layer, and the first conductive type
semiconductor layer to upwardly expose a portion of the first
conductive type semiconductor layer.
[0009] 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.
Advantageous Effects
[0010] The embodiments can provide a light emitting device and a
method for manufacturing the light emitting device.
[0011] The embodiments can provide a light emitting device and a
method for manufacturing the light emitting device, which has
improved light extraction efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of a light emitting diode
according to a first embodiment.
[0013] FIG. 2 is a cross-sectional view taken along line I-I' of
the light emitting diode according to the first embodiment.
[0014] FIG. 3 is a perspective view of a light emitting diode
according to a second embodiment.
[0015] FIG. 4 is a cross-sectional view taken along line II-II' of
the light emitting diode according to the second embodiment.
[0016] FIGS. 5 through 10 are views illustrating a method for
manufacturing a light emitting diode according to an
embodiment.
BEST MODE FOR CARRYING OUT THE INVENTION
[0017] Reference will now be made in detail to the embodiments of
the present disclosure, examples of which are illustrated in the
accompanying drawings.
[0018] In the descriptions of embodiments, it will be understood
that when a layer (or film), a region, a pattern, or a structure is
referred to as being "on/under" a substrate, a layer (or film), a
region, a pad, or patterns, it can be directly on the substrate,
the layer (or film), the region, the pad, or the patterns, or
intervening layers may also be present. Also, Further, the
reference about `on` and `under` each layer will be made on the
basis of the drawings.
[0019] In the drawings, the dimension of each of elements may be
exaggerated for clarity of illustration, and the dimension of each
of the elements may be different from the actual dimension of each
of the elements.
[0020] Hereinafter, a light emitting device and a method for
manufacturing the same will be described with reference to the
accompanying drawings.
[0021] FIG. 1 is a perspective view of a light emitting diode
according to a first embodiment. FIG. 2 is a cross-sectional view
taken along line I-I' of the light emitting diode according to the
first embodiment.
[0022] Referring to FIGS. 1 and 2, a light emitting diode according
to a first embodiment may include a substrate 10, a buffer layer
20, an undoped GaN layer 30, a first conductive type semiconductor
layer 40, an active layer 50, and a second conductive type
semiconductor layer 60.
[0023] A first electrode layer 80 may be formed on the first
conductive type semiconductor layer 40, and a second electrode
layer 90 may be formed on the second conductive type semiconductor
layer 60.
[0024] Although not shown, a third conductive type impurity layer
doped with a first conductive type impurity may be formed on the
second conductive type semiconductor layer 60.
[0025] The light emitting diode according to the first embodiment
may include an opening 110 to form the first electrode layer 80
therein. The opening 110 may be formed by selectively removing the
second conductive type semiconductor layer 60, the active layer 50,
and the first conductive type semiconductor layer 40.
[0026] The upper side of the first conductive type semiconductor
layer 40 may be exposed by the opening 110, and then the first
electrode layer 80 may be formed on the first conductive type
semiconductor layer 40.
[0027] Although not shown, the first electrode layer 80 and the
second electrode layer 90 may be electrically connected to an
external power source. Also, an ohmic contact layer may be formed
between the second conductive type semiconductor layer 60 and the
second electrode layer 90. The ohmic contact layer may be formed
with a transparent electrode.
[0028] A light extraction layer 70 may be formed on the second
conductive type semiconductor layer 60.
[0029] The light extraction layer 70 may be formed on a peripheral
portion of the second conductive type semiconductor layer 60.
Accordingly, the light extraction layer 70 may be disposed to
surround the exposed portion of the second conductive type
semiconductor layer 60 and the opening 110.
[0030] The light extraction layer 70 may also be formed on all of
the peripheral portions of the second conductive type semiconductor
layer 60.
[0031] The side surface of the light extraction layer 70 may be
formed on the same vertical plane as the side surface of the second
conductive type semiconductor layer 60.
[0032] The light extraction layer 70 may allow light from the
active layer 50 to be emitted to the outside more efficiently.
[0033] The light extraction layer 70 may be formed to have an
inclined surface 71 in an upwardly exposed direction of the second
conductive type semiconductor layer 60. The inclined surface 71 may
be inclined at an angle of about 58 degrees to about 63 degrees
with respect to the upper surface of the second conductive type
semiconductor layer 60.
[0034] The light extraction layer 70 may be formed to have a
refractive index smaller than or equal to that of the second
conductive type semiconductor layer 60. For example, the second
conductive type semiconductor layer 60 may be formed of GaN, and
may have a refractive index of about 2.33 with respect to light
having a wavelength of about 450 nm. The light extraction layer 70
may be formed of Al.sub.xGa.sub.1-xN.sub.y (0.ltoreq.x.ltoreq.1),
and may have a refractive index of about 2.12 to about 2.33 with
respect to light having a wavelength of 450 nm. The light
extraction layer 70 may be formed of AlGaN.
[0035] As shown by the arrow in FIG. 1, since the light extraction
layer 70 having a refractive index smaller than or equal to that of
the second conductive type semiconductor layer 60 is formed on the
second conductive type semiconductor layer 60, there is an
increased possibility that light generated in the active layer 50
may be reflected by the upper surface of the second conductive type
semiconductor layer 60 to be emitted to the outside without being
again incident to the inside. Particularly, the inclined surface 71
of the light extraction layer 70 may allow the light to be emitted
in the upward direction more smoothly.
[0036] Although not shown, the ohmic contact layer may be formed
between the second conductive type semiconductor layer 60 and the
light extraction layer 70.
[0037] FIG. 3 is a perspective view of a light emitting diode
according to a second embodiment. FIG. 4 is a cross-sectional view
taken along line II-II' of the light emitting diode according to
the second embodiment.
[0038] Referring to the FIGS. 3 and 4, the light emitting diode
according to the second embodiment may be similar to the light
emitting diode described in the first embodiment.
[0039] However, there is a difference in that the light emitting
diode according to the first embodiment is formed to have the
opening 110 exposing the first conductive type semiconductor layer
40 upwardly to form the first electrode layer 80, while the light
emitting diode according to the second embodiment is formed to have
the opening 110 of FIG. 1 to be opened in the direction of the side
surface as well.
[0040] For this, portions of the second conductive type
semiconductor layer 60, the active layer 50, the first conductive
type semiconductor layer 40, and the light extraction layer 70 may
be selectively removed.
[0041] The light emitting diode according to the second embodiment
has an advantage in that a process for electrically connecting the
first electrode layer 80 to an external power source through a wire
can be more easily performed.
[0042] FIGS. 5 through 10 are views illustrating a method for
manufacturing a light emitting diode according to an
embodiment.
[0043] Referring to FIG. 5, a buffer layer 20, an undoped GaN layer
30, a first conductive type semiconductor layer 40, an active layer
50, and a second conductive type semiconductor layer 60 may be
formed on a substrate 10. A mask layer 100 may be formed on the
second conductive type semiconductor layer 60 to form a light
extraction layer 70.
[0044] For example, the substrate 10 may be formed of at least one
of Al.sub.2O.sub.3, Si, SiC, GaAs, ZnO, and MgO.
[0045] The buffer layer 20 may reduce a difference in the lattice
constants between the substrate 10 and the nitride semiconductor
layer stacked over the substrate, and may be formed in a stacked
structure of materials such as AlInN/GaN, In.sub.xGa.sub.1-xN/GaN,
and Al.sub.xIn.sub.yGa.sub.1-x-yN/In.sub.xGa.sub.1-xN/GaN.
[0046] The undoped GaN layer 30 may be formed by injecting a gas
including NH.sub.3 and TMGa into a chamber.
[0047] The first conductive type semiconductor layer 40 may be a
nitride semiconductor layer doped with a first conductive type
impurity. For example, the first conductive type impurity may be an
n-type impurity. The first conductive type semiconductor layer 40
may be formed of a GaN layer including Si as an n-type
impurity.
[0048] The active layer 50 may be formed in a single quantum well
structure or a multi-quantum well structure. For example, the
active layer 50 may be formed in a stacked structure of InGaN well
layer/GaN barrier layer.
[0049] The second conductive type semiconductor layer 60 may be a
nitride semiconductor layer doped with a second conductive type
impurity. For example, the second conductive type impurity may be a
p-type impurity. The second conductive type semiconductor layer 60
may be formed of a GaN layer including Mg as a p-type impurity.
[0050] A third conductive type semiconductor layer (not shown) may
be a nitride semiconductor layer doped with a first conductive type
impurity. For example, the first conductive type impurity may
include an n-type impurity such as Si.
[0051] The mask layer 100 may be formed of a silicon oxide
(SiO.sub.2). The mask layer 100 may be patterned to form the light
extraction layer 70 according to an embodiment.
[0052] Referring to FIG. 6, the light extraction layer 70 may be
formed on the second conductive type semiconductor layer 60 after
the mask layer 100 is formed.
[0053] The light extraction layer 70 may be formed of
Al.sub.xGa.sub.1-xN.sub.y (0.ltoreq.x.ltoreq.1). For example, the
Al.sub.xGa.sub.1-xN.sub.y may be formed by supplying NH.sub.3, TMGa
and TMAl at a temperature of about 800.quadrature. to about
1,000.quadrature.. For example, the light extraction layer 70 may
be formed of AlGaN.
[0054] The light extraction layer 70 may be formed to have an
inclined surface 71 inclined at an angle of about 58 degrees to
about 63 degrees with respect to the upper surface of the second
conductive type semiconductor layer 60 during growth process.
[0055] The mask layer 100 may be removed as shown in FIG. 7.
[0056] Referring to FIG. 8, a scribing process may be performed
around the light extraction layer 70.
[0057] The scribing process is to divide a semiconductor layer into
pieces to make a plurality of light emitting devices. While a
cross-sectional view has been illustrated in FIG. 8, the
semiconductor layer may be divided in a shape similar to a cube as
shown in FIGS. 1 and 3.
[0058] Accordingly, the light extraction layer 70 may be disposed
on the peripheral portion of the second conductive type
semiconductor layer 60. The side surface of the light extraction
layer 70 may be formed on the same vertical plane as the side
surface of the second conductive type semiconductor layer 60.
[0059] Here, an ohmic contact layer (not shown) may be formed on
the second conductive type semiconductor layer 60, and then the
mask layer 100 may be formed on the ohmic contact layer.
Thereafter, the light extraction layer 70 may be formed over the
ohmic contact layer.
[0060] Alternatively, after the light extraction layer 70 is formed
on the second conductive type semiconductor layer 60, the ohmic
contact layer may be formed on the second conductive type
semiconductor layer 60 on which the light extraction layer 70 is
not formed.
[0061] Referring to FIG. 9, a mask pattern (not shown) may be
formed over the second conductive type semiconductor layer 60 and
the light extraction layer 70 described in FIG. 8, and then the
second conductive type semiconductor layer 60, the active layer 50,
and the first conductive type semiconductor layer 40 may be
selectively etched to form the opening 110 as described in FIGS. 1
and 2.
[0062] Alternatively, the light extraction layer 70, the second
conductive type semiconductor layer 60, the active layer 50, and
the first conductive type semiconductor layer 40 may be selective
etched along the mask pattern to form the opening as described in
FIGS. 3 and 4.
[0063] Referring to FIG. 10, a first electrode layer 80 may be
formed on the first conductive type semiconductor layer 40, and
then a second electrode layer 90 may be formed on the second
conductive type semiconductor layer 60.
[0064] Accordingly, a light emitting diode can be manufactured as
described in FIG. 1.
[0065] Thereafter, a process for electrically connecting the first
and second electrode layers 80 and 90 to an external power source
through a wire may be performed, and a process for forming a
molding member on the second conductive type semiconductor layer 60
and the light extraction layer 70 may be performed.
[0066] 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
[0067] The embodiments can be applied to light emitting devices
used as a light source.
* * * * *