U.S. patent application number 12/899926 was filed with the patent office on 2011-08-04 for light emitting device, method of manufacturing the same, light emitting device package and lighting system.
Invention is credited to Dae Sung KANG, Jung Min Won.
Application Number | 20110186889 12/899926 |
Document ID | / |
Family ID | 43838005 |
Filed Date | 2011-08-04 |
United States Patent
Application |
20110186889 |
Kind Code |
A1 |
KANG; Dae Sung ; et
al. |
August 4, 2011 |
LIGHT EMITTING DEVICE, METHOD OF MANUFACTURING THE SAME, LIGHT
EMITTING DEVICE PACKAGE AND LIGHTING SYSTEM
Abstract
A light emitting device includes an active layer formed between
first and second semiconductor layers. The first semiconductor
layer includes a first surface facing the active layer, a second
surface opposing the first surface, and a side surface that
includes a stepped portion. The stepped portion causes the side
surface to extend beyond one of the first surface or second surface
of the first semiconductor layer. A light emitting device may also
be formed with a buffer layer that includes a stepped portion, and
a light emitting device package and system may be formed from the
light emitting devices.
Inventors: |
KANG; Dae Sung; (Seoul,
KR) ; Won; Jung Min; (Seoul, KR) |
Family ID: |
43838005 |
Appl. No.: |
12/899926 |
Filed: |
October 7, 2010 |
Current U.S.
Class: |
257/98 ;
257/E33.001; 257/E33.067; 438/22 |
Current CPC
Class: |
H01L 33/32 20130101;
H01L 33/46 20130101; H01L 2224/48091 20130101; H01L 33/12 20130101;
H01L 33/20 20130101; H01L 33/06 20130101; H01L 33/22 20130101; H01L
2924/00014 20130101; H01L 2224/48091 20130101; H01L 33/007
20130101 |
Class at
Publication: |
257/98 ; 438/22;
257/E33.067; 257/E33.001 |
International
Class: |
H01L 33/60 20100101
H01L033/60; H01L 33/12 20100101 H01L033/12 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 4, 2010 |
KR |
10-2010-0010204 |
Claims
1. A light emitting device comprising: a first semiconductor layer;
a second semiconductor layer; and an active layer between the first
and second semiconductor layers, wherein the first semiconductor
layer includes: (a) a first surface facing the active layer, (b) a
second surface opposing the first surface, and (c) a side surface
that includes a stepped portion, wherein the stepped portion causes
the side surface to extend beyond one of the first surface or
second surface.
2. The device of claim 1, wherein an area of the first surface is
greater than an area of the second surface.
3. The device of claim 2, wherein the area of the second surface is
less than the area of the first surface as a result of the stepped
portion.
4. The device of claim 1, wherein an area of the first surface is
less than an area of the second surface.
5. The device of claim 1, wherein the first semiconductor layer is
a first conductivity type and the second semiconductor layer is a
second conductivity type.
6. The device of claim 1, further comprising: a buffer layer,
wherein a first semiconductor layer is located between the buffer
layer and the active layer, the first semiconductor layer is of a
first conductivity type, and the second semiconductor layer is of a
second conductivity type.
7. The device of claim 6, wherein the buffer layer is formed on a
first portion of the first conductivity type semiconductor, and
wherein the device further comprises: a first electrode on the
first semiconductor layer where the buffer layer is not formed, and
a second electrode under the second semiconductor layer.
8. The device of claim 7, wherein the buffer layer is divided into
first and second sections disposed on the first semiconductor
layer, the first and second sections of the buffer layer separated
to expose a portion of the first semiconductor layer, the first
electrode electrically coupled to the exposed portion of the first
semiconductor layer.
9. The device of claim 6, wherein the buffer layer is an undoped
layer.
10. The device of claim 6, wherein the buffer layer is a doped
layer.
11. The device of claim 1, further comprising: at least one
reflector to reflect light emitted from the active layer.
12. The device of claim 11, wherein the reflector is located
adjacent the first semiconductor layer.
13. The device of claim 12, wherein the reflector includes: a
protrusion that extends from a surface of a substrate that supports
or is coupled to the first semiconductor layer.
14. The device of claim 1, further comprising: at least one
diffuser, located on the second surface of the first semiconductor
layer, to diffuse light emitted from the active layer.
15. The device of claim 14, wherein the diffuser extends into the
second surface of the first semiconductor layer.
16. The device of claim 15, wherein the diffuser includes a recess
that extends into the second surface of the first semiconductor
layer.
17. A light emitting device comprising: a buffer layer; a first
semiconductor layer; a second semiconductor layer; and an active
layer between the first and second semiconductor layers, wherein:
the first semiconductor layer is between the buffer layer and
active layer, the active layer is between the first and second
semiconductor layers, and wherein a bottom surface of the buffer
layer has an area smaller than an area of at least one of the
surfaces of the first semiconductor layer.
18. The device of claim 17, wherein a side surface of the buffer
layer includes: a stepped portion which causes a top surface of the
buffer layer facing the first semiconductor layer to have an area
greater than the bottom surface of the buffer layer.
19. The device of claim 17, wherein a side surface of the buffer
layer includes: a stepped portion which causes the side surface of
the buffer layer to extend beyond at least one of a top surface or
the bottom surface of the buffer layer.
20. The device of claim 17, wherein the buffer layer is a doped
layer.
21. The device of claim 17, wherein the buffer layer is an undoped
layer.
22. The device of claim 17, further comprising: at least one
reflector to reflect light emitted from the active layer.
23. The device of claim 22, wherein the reflector is adjacent the
buffer layer.
24. The device of claim 23, wherein the reflector includes: a
protrusion that extends from a surface of a substrate that supports
or is coupled to the buffer layer.
25. A light emitting device package comprising the light emitting
device of claim 1.
26. A light emitting device package comprising the light emitting
device of claim 17.
27. A lighting system comprising a light emitting device as recited
in claim 1, wherein said device is coupled to a substrate of a
light emitting module.
28. A method of manufacturing a light emitting device, comprising:
forming a mask layer on a substrate to define a region of a light
emitting device; forming a semiconductor layer of a first
conductivity type, an active layer, and a semiconductor layer of a
second conductivity type at said region; selectively removing the
mask layer; and forming first and second electrodes electrically
coupled to the first and second semiconductor layers respectively,
wherein one of the semiconductor layers is formed to include a
first surface facing the active layer, a second surface opposing
the first surface, and a side surface that includes a stepped
portion, and wherein the stepped portion causes the side surface to
extend beyond one of the first surface or second surface.
29. A method of manufacturing a light emitting device, comprising:
forming a mask layer on a substrate to define a region of a light
emitting device; forming a semiconductor layer of a first
conductivity type, an active layer, and a semiconductor layer of a
second conductivity type at said region; selectively removing the
mask layer; and forming first and second electrodes electrically
coupled to the first and second semiconductor layers respectively,
wherein one of the semiconductor layers is formed to include a
first surface facing the active layer, said method further
comprising: forming a buffer layer coupled to the first and second
semiconductor layers and the active layer, wherein a bottom surface
of the buffer layer has an area smaller than an area of at least
one of the surfaces of the semiconductor layer of the first
conductivity type or the second conductivity type.
30. The method of claim 29, wherein the buffer layer includes a
stepped portion that causes the bottom surface of the buffer layer
to have an area smaller than an area of at least one of the
surfaces of the semiconductor layer of the first conductivity type
or the second conductivity type.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority under 35 U.S.C.
.sctn.119 of Korean Patent Application No. 10-2010-0010204 filed on
Feb. 4, 2010, which is hereby incorporated by reference in its
entirety.
BACKGROUND
[0002] 1. Field
[0003] One or more embodiments disclosed herein relate to the
emission of light.
[0004] 2. Background
[0005] A light emitting diode (LED) is a semiconductor device that
converts an electrical signal into light. These devices typically
have a stack structure which includes a semiconductor layer of a
first conductivity type, an active layer, and a semiconductor layer
of a second conductivity type. Because of their size, LEDs have
proven desirable for many applications. However, improvements are
still needed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIGS. 1 to 4 are sectional diagrams showing a first
embodiment of a light emitting device and a various stages of its
manufacture.
[0007] FIGS. 5 to 7 are sectional diagrams showing a second
embodiment of a light emitting device and various stages of its
manufacture.
[0008] FIGS. 8 to 11 are sectional diagrams showing a third
embodiment of a light emitting device and various stages of its
manufacture.
[0009] FIGS. 12 to 15 are sectional diagrams showing a fourth
embodiment of a light emitting device and various stages of its
manufacture.
[0010] FIG. 16 is a diagram showing a mask layer and
protrusions.
[0011] FIG. 17 is a diagram showing the same or another mask
layer.
[0012] FIG. 18 is a diagram showing one embodiment of a light
emitting device package that may include any of the aforementioned
embodiments of the light emitting device.
[0013] FIG. 19 is a diagram showing one embodiment of a backlight
unit that may include any of the aforementioned embodiments of the
light emitting device or package.
[0014] FIG. 20 is a diagram showing one embodiment of a lighting
unit that may include any of the aforementioned embodiments of the
light emitting device or package.
DETAILED DESCRIPTION
[0015] FIGS. 1 to 4 show one embodiment of a light emitting device
and various stages of its manufacture. Referring first to FIG. 4,
the light emitting device includes a light emitting structure layer
60 formed from a semiconductor layer 30 of a first conductivity
type, an active layer 40 and a semiconductor layer 50 of a second
conductivity type, all of which are supported by a growth substrate
10. The LED further includes a first electrode 70 formed on the
first conductivity type semiconductor layer 30, and a second
electrode 80 formed on the second conductivity type semiconductor
layer 50.
[0016] A plurality of protrusions 11 are formed on the growth
substrate 10. The protrusions 11 may be in a semi-spherical shape
or another shape, and in terms of materials may be formed, for
example, from one or more of SiO.sub.2, SiN, GaO, ZnO, or ITO. The
protrusions 11 may serve to enhance the light extraction efficiency
of the light emitting device by allowing light emitted from the
active layer 40 to be scattered. The protrusions 11 may provided in
various numbers and/or shapes in addition to those shown in FIG.
4.
[0017] As indicated, the semiconductor layers on the growth
substrate 10 include a first semiconductor layer, a second
semiconductor layer, and the active layer between the first
semiconductor layer and the second semiconductor layer. In the
current embodiment, the first semiconductor layer is implemented by
the first conductivity type semiconductor layer 30 and the second
semiconductor layer is implemented by the second conductivity type
semiconductor layer 50.
[0018] The first conductivity type semiconductor layer 30 is formed
with a stepped portion 31 at a lower edge surface thereof. The
stepped portion 31 may be formed by extending the lower edge
surfaces of the first conductivity type semiconductor layer 30.
Some portions of the first conductivity type semiconductor layer 30
are spaced apart from the growth substrate 10. Also, in one
embodiment, at least a portion of the stepped portion 31 and the
protrusions 11 may be disposed on the same plane.
[0019] The first conductivity type semiconductor layer 30 includes
a first surface contacting the active layer 40 and a second surface
oppositely facing the first surface. The area of the second surface
may be smaller than a maximum area of the first conductivity type
semiconductor layer due to the stepped portion 31.
[0020] One embodiment of a method for manufacturing the light
emitting device shown in FIG. 4 will now be discussed with
reference to FIGS. 1 to 4.
[0021] Referring to FIG. 1, a growth substrate 10 is prepared and a
plurality of protrusions 11 and a mask layer 12 are formed on the
growth substrate 10. The growth substrate 10 may be formed, for
example, of one or more of sapphire (Al.sub.2O.sub.3), SiC, Si,
GaAs, ZnO, MgO, GaN, Glass or Ga.sub.2O.sub.3. The mask layer 12
may be formed of the same material as that of the protrusions 11,
e.g., SiO.sub.2, SiN, GaO, ZnO, or ITO.
[0022] FIG. 16 shows an example of a plane view of mask layer 12
and protrusions 11. As shown in FIG. 16, the mask layer 12 may be
formed so that the growth substrate 10 is exposed so that the light
emitting structure layer 60 may be grown. That is, a plurality of
light emitting structure layer growth regions A may be defined by
the mask layer 12. The light emitting structure layer 60 may not be
grown on the mask layer 12, and in such a case the light emitting
structure layer 60 on the light emitting structure layer growth
regions A may be grown so that they are separated from each other
by the mask layer 12. The protrusions may be partially formed on
the light emitting structure layer growth regions A of the growth
substrate 10 where the mask layer 12 is not formed.
[0023] FIG. 17 shows another view of mask layer 12. As shown, the
mask layer 12 formed on the growth substrate 10 and the light
emitting structure layer growth regions A are defined by mask layer
12. Also, the protrusions 11 are not formed on the growth substrate
10, but a protrusion pattern 12a may be formed on a side surface of
the mask layer 12. This or another protrusion pattern corresponding
to protrusion pattern 12a may be formed on a side surface of the
first conductivity type semiconductor layer 30 grown on the light
emitting structure layer growth regions A.
[0024] Referring to FIG. 2, a light emitting structure layer 60,
including the first conductivity type semiconductor layer 30, an
active layer 40 and a second conductivity type semiconductor layer
50, is grown on the growth substrate 10 on which the mask layer 12
and the protrusions 11 are formed.
[0025] The first conductivity type semiconductor layer 30 is grown
on the growth substrate 10 to cover the protrusions 11 through a
horizontal growth and a vertical growth and to partially cover the
mask layer 12.
[0026] The mask layer 12 allows the light emitting structure layer
60 to be grown in multiple chip units on a substrate, for example,
by dividing the growth substrate 10 into a plurality of light
emitting structure layer growth regions A on which the light
emitting structure 60 is grown. Thus, instead of scribing the
substrate into individual chip units first (that is, right after
formation of the light emitting structure layer), the light
emitting structure layer is grown into multiple chip units on a
single substrate.
[0027] More specifically, when the aforementioned scribing
technique is used, the crystallinity of a cleavage surface may not
be good. As a result, leakage current may flow into the cleavage
surface. However, when the light emitting structure layer is grown
onto the substrate as separated or divided chip units, the
resulting light emitting structure layer 60 is grown into a high
quality thin layer having improved properties in terms of
crystallinity of the side surface.
[0028] The first conductivity type semiconductor layer 30 may be
grown, for example, as or into a GaN-based semiconductor layer
including an n-type impurity such as silicon (Si), and the second
conductivity type semiconductor layer 50 may be grown as or into a
GaN-based semiconductor layer including a p-type impurity such as
Mg.
[0029] The active layer 40 may be formed of InGaN layer/GaN layer
having a single quantum well structure or multi-quantum well
structure by supplying ammonia (NH.sub.3), trimethylgallium (TMGa),
and trimethylindium (TMIn).
[0030] Referring to FIG. 3, a mesa etching step for partially
removing the second conductivity type semiconductor layer 50, the
active layer 40 and the first conductivity type semiconductor layer
30 is performed. By mesa etching, some of the first conductivity
type semiconductor layer 30 is exposed in an upward direction.
Thereafter, a first electrode 70 is formed on the first
conductivity type semiconductor layer 30, and a second electrode 80
is formed on the second conductivity type semiconductor layer
50.
[0031] Referring to FIG. 4, the growth substrate 10 and the mask
layer 12 are cut to divide the growth substrate 10 and the light
emitting structure layer 60 into chip units. The growth substrate
10 may be cut by a scribing method or breaking method, and the mask
layer 12 may be removed by an etching method.
[0032] At this time, the mask layer 12 may be partially or
completely removed. In the case where the mask layer 12 is removed
completely as shown in FIG. 4, the stepped portion 31 is formed at
a lower edge region of the first conductivity type semiconductor
layer 30.
[0033] In the case where mask layer 12 is formed as shown in FIG.
17, a protrusion pattern may be formed on a side surface of the
first conductivity type semiconductor layer.
[0034] FIGS. 5 to 7 show a second embodiment of a light emitting
device and various stages of its manufacture. Referring first to
FIG. 7, the second embodiment of the light emitting device includes
an undoped nitride layer 20 is formed on a growth substrate 10 and
a light emitting structure layer 60 formed on the undoped nitride
layer. The light emitting structure layer includes a first
conductivity type semiconductor layer 30, an active layer 40, and a
second conductivity type semiconductor layer 50. In addition, the
LED includes a first electrode 70 formed on the first conductivity
type semiconductor layer 30, and a second electrode 80 formed on
the second conductivity type semiconductor layer 50.
[0035] A plurality of protrusions 11 are formed on the growth
substrate 10. The protrusions 11 may be in a semi-spherical shape
or another shape, and may be formed, for example, of one or more of
SiO.sub.2, SiN, GaO, ZnO, or ITO. The protrusions 11 may serve to
enhance the light extraction efficiency of the light emitting
device by allowing light emitted from the active layer 40 to be
scattered. The protrusions 11 may be provided in various numbers
and/or shapes in addition to those shown.
[0036] As indicated, the semiconductor layers on the growth
substrate 10 include a first semiconductor layer, a second
semiconductor layer, and the active layer between the first
semiconductor layer and the second semiconductor layer. In the
current embodiment, the first semiconductor layer includes the
undoped nitride layer 20 and the first conductivity type
semiconductor layer 30, and the second semiconductor layer is
includes the second conductivity type semiconductor layer 50.
[0037] The undoped nitride layer 20 is formed with a stepped
portion 21 at one or more lower edge surfaces thereof. Some
portions of the undoped nitride layer 20 may be spaced apart from
the growth substrate 10. Also, at least a portion of the stepped
portion 21 and the protrusions 11 may be disposed on the same
plane.
[0038] The undoped nitride layer 20 may include a first surface
contacting the first conductivity type semiconductor layer 30 and a
second surface oppositely facing the first surface, and the area of
the second surface may be smaller than a maximum area of the first
conductivity type semiconductor layer due to the stepped portion
21.
[0039] One method for manufacturing the second embodiment of the
light emitting device will now be described with reference to FIGS.
5 to 7. Referring to FIG. 5, a growth substrate 10 is prepared and
a plurality of protrusions 11 and a mask layer 12 are formed on the
growth substrate 10. The growth substrate 10 may be formed, for
example, from one or more of sapphire (Al.sub.2O.sub.3), SiC, Si,
GaAs, ZnO, MgO, GaN, Glass or Ga.sub.2O.sub.3. The mask layer 12
may be formed of the same material as the protrusions 11 and may
be, for example, formed from one or more of SiO.sub.2, SiN, GaO,
ZnO, or ITO.
[0040] An undoped nitride layer 20 is grown on the growth substrate
10 on which the mask layer 12 and the protrusions 11 are formed. A
light emitting structure layer 60 including a first conductivity
type semiconductor layer 30, an active layer 40 and a second
conductivity type semiconductor layer 50 is grown on the undoped
nitride layer 20.
[0041] The undoped nitride layer 20 is grown on the growth
substrate 10 to cover the mask layer 12 and the protrusions 11
through a horizontal growth and a vertical growth. Although the
undoped nitride layer 20 may not intentionally doped with a first
conductivity type impurity, the undoped nitride layer 20 is a
nitride layer which may have the first conductivity type
conductivity, and may be, for example, formed of Un-GaN layer.
[0042] The first conductivity type semiconductor layer 30 may be
formed, for example, of a GaN-based semiconductor layer including
an n-type impurity such as silicon (Si), and the second
conductivity type semiconductor layer 50 may be formed of a
GaN-based semiconductor layer including a p-type impurity such as
Mg.
[0043] The active layer 40 may be formed of InGaN layer/GaN layer
having a single quantum well structure or multi-quantum well
structure by supplying ammonia (NH.sub.3), trimethylgallium (TMGa),
and trimethylindium (TMIn).
[0044] Referring to FIG. 6, the result of a mesa etching technique
is shown for partially removing the second conductivity type
semiconductor layer 50, the active layer 40, and the first
conductivity type semiconductor layer 30. By mesa etching, some of
the first conductivity type semiconductor layer 30 is exposed in an
upward direction.
[0045] Thereafter, a first electrode 70 is formed on the first
conductivity type semiconductor layer 30 and a second electrode 80
is formed on the second conductivity type semiconductor layer
50.
[0046] Referring to FIG. 7, the growth substrate 10 and the mask
layer 12 are cut to divide the growth substrate 10 and the light
emitting structure layer 60 into chip units. The growth substrate
10 may be cut by a scribing method or a breaking method, and the
mask layer 12 may be removed by an etching method. At this time,
the mask layer 12 may be completely or partially removed. In the
case where the mask layer 12 is removed completely as shown in FIG.
7, the stepped portion 21 is formed at a lower edge region of the
undoped nitride layer 20. Also, in the case where the mask layer 12
is formed as shown in FIG. 17, a protrusion pattern may be formed
on a side surface of the undoped nitride layer where the stepped
portion 21 is formed.
[0047] FIGS. 8 to 11 show a third embodiment of a light emitting
device and various stages of its manufacture. Referring first to
FIG. 11, the light emitting device includes a light emitting
structure layer 60 formed from a first conductivity type
semiconductor layer 30, an active layer 40, and a second
conductivity type semiconductor layer 50. A first electrode 70 is
formed on the first conductivity type semiconductor layer 30 and a
second electrode 110 is formed under the second conductivity type
semiconductor layer 50.
[0048] The second electrode 110 includes an ohmic contact layer 111
under the second conductivity type semiconductor layer 50, a
reflective layer 112 under the ohmic contact layer 111, and a
conductivity supporting substrate 113 under the reflective layer
112.
[0049] As indicated, the semiconductor layers on the second
electrode 110 include a first semiconductor layer, a second
semiconductor layer, and the active layer between the first
semiconductor layer and the second semiconductor layer. In the
current embodiment, the first semiconductor layer is implemented by
the first conductivity type semiconductor layer 30, and the second
semiconductor layer is implemented by the second conductivity type
semiconductor layer 50.
[0050] The first conductivity type semiconductor layer 30 is formed
with a stepped portion 31 at an upper side surface thereof and with
upper grooves 32 at an upper surface thereof. The upper grooves 32
may act as photonic crystals which allow the light emitted from the
active layer 40 to be effectively extracted to an outside.
[0051] The first conductivity type semiconductor layer 30 includes
a first surface contacting the active layer 40 and a second surface
oppositely facing the first surface. The area of the second surface
may be smaller than a maximum area of the first conductivity type
semiconductor layer due to the stepped portion 31.
[0052] One method for manufacturing the third embodiment of the
light emitting device is shown with reference to FIGS. 8 to 11.
Referring to FIG. 8, a growth substrate 10 is prepared and a
plurality of protrusions 11 and a mask layer 12 are formed on the
growth substrate 10. The growth substrate 10 may be formed, for
example, from one or more of sapphire (Al.sub.2O.sub.3), SiC, Si,
GaAs, ZnO, MgO, GaN, Glass or Ga.sub.2O.sub.3, and mask layer 12
may be formed of the same material as protrusions 11, e.g., one or
more of SiO.sub.2, SiN, GaO, ZnO, or ITO.
[0053] A light emitting structure layer 60, including a first
conductivity type semiconductor layer 30, an active layer 40, and a
second conductivity type semiconductor layer 50, is grown on the
growth substrate 10 on which the mask layer 12 and the protrusions
11 are formed. The first conductivity type semiconductor layer 30
is grown on the growth substrate 10 to cover the mask layer 12 and
the protrusions 11 through a horizontal growth and a vertical
growth.
[0054] The first conductivity type semiconductor layer 30 may be
formed, for example, from a GaN-based semiconductor layer including
an n-type impurity such as silicon (Si), and the second
conductivity type semiconductor layer 50 may be formed, for
example, from a GaN-based semiconductor layer including a p-type
impurity such as Mg.
[0055] The active layer 40 may be formed of InGaN layer/GaN layer
having a single quantum well structure or multi-quantum well
structure by supplying ammonia (NH.sub.3), trimethylgallium (TMGa),
and trimethylindium (TMIn).
[0056] Referring to FIG. 9 since the light emitting structure layer
60 is grown into multiple chip unit on the substrate at ares
defined by mask layer 12, a spacing exists between the light
emitting structure layers 60 that are adjacent to each other.
Therefore, a protective layer 90 is formed between the light
emitting structure layer 60 and light emitting structure layer 60.
The protective layer 90 may be formed of a material such as
polyimide or SOG or another material.
[0057] A second electrode 110 is formed on the light emitting
structure layer 60 and the protective layer 90. The second
electrode layer 110 may be formed by first forming an ohmic contact
layer 111, forming a reflective layer 112 on the ohmic contact
layer 111, and forming a conductivity supporting substrate 113 on
the reflective layer 112.
[0058] The conductivity supporting substrate 113 may be formed to
include, for example, at least one of copper (Cu), titanium (Ti),
molybdenum (Mo), chromium (Cr), nickel (Ni), aluminum (Al),
platinum (Pt), gold (Au), tungsten (W), or conductivity
semiconductor material. The reflective layer 112 may be formed from
a metal including, for example, at least one of silver (Ag),
aluminum (Al), copper (Cu), or nickel (Ni) having a high
reflectivity. Also, the ohmic contact layer 111 may be formed of a
transparent conductivity oxide, such as indium tin oxide (ITO),
aluminum-doped zinc oxide (AZO), indium zinc oxide (IZO), antimony
tin oxide (ATO), or zinc indium tin oxide (ZITO).
[0059] Referring to FIG. 10, the growth substrate 10, mask layer
12, protective layer 90, and protrusions 11 are removed. The growth
substrate 10 may be removed using, for example, a laser lift-off
method or a chemical lift-off method. Since the mask layer 12 and
the protrusions 11 are disposed between the growth substrate 10 and
the light emitting structure layer 60, the growth substrate 10 can
be easily separated from the light emitting structure layer 60.
That is, because the mask layer 12 and the protrusions 11 are not
strongly bonded to the light emitting structure layer 60, the more
wide the area of the mask layer 12 and the protrusions 11, the
easier the separation of the growth substrate 10.
[0060] As the growth substrate 10 is separated, the protrusions 11
and the mask layer 12 can be easily separated, and the protective
layer 90 can be removed by using an etchant. As the protrusions 11
and the mask layer 12 are removed, upper grooves 32 and stepped
portions 31 are formed in the first conductivity type semiconductor
layer 30. Referring to FIG. 11, a first electrode 70 is formed on
the first conductivity type semiconductor layer 30 and then the
second electrode 110 is separated.
[0061] FIGS. 12 to 15 show a fourth embodiment of a light emitting
device and various stages of its manufacture. Referring to FIG. 15,
the light emitting device includes a light emitting structure layer
60 formed from a first conductivity type semiconductor layer 30, an
active layer 40, and a second conductivity type semiconductor layer
50 is formed, and an undoped nitride layer 20 is formed on the
first conductivity type semiconductor layer 30.
[0062] A first electrode 70 is formed on the first conductivity
type semiconductor layer 30 exposed by selectively removing the
undoped nitride layer 20, and a second electrode 80 is formed under
the second conductivity type semiconductor layer 50.
[0063] As indicated, the semiconductor layers on the second
electrode 110 include a first semiconductor layer, a second
semiconductor layer, and the active layer between the first
semiconductor layer and the second semiconductor layer. In the
current embodiment, the first semiconductor layer is implemented by
the undoped nitride layer 20 and the first conductivity type
semiconductor layer 30, and the second semiconductor layer is
implemented by the second conductivity type semiconductor layer
50.
[0064] The undoped nitride layer 20 is formed with a stepped
portion 21 at an upper side surface thereof and with upper grooves
22 at an upper surface thereof. The upper grooves 22 may act as
photonic crystals, which allow the light emitted from the active
layer 40 to be effectively extracted to an outside. The undoped
layer may be formed from a material other than an nitride, and the
same is true of the undoped layer in the third and other
embodiments described herein.
[0065] The undoped nitride layer 20 includes a first surface
contacting the first conductivity type semiconductor layer 30 and a
second surface oppositely facing the first surface. The area of the
second surface may be smaller than a maximum area of the first
conductivity type semiconductor layer due to the stepped portion
21.
[0066] One method for manufacturing the fourth embodiment of the
light emitting device will now be described with reference to FIGS.
12 to 15. Referring to FIG. 12, a growth substrate 10 is prepared
and a plurality of protrusions 11 and a mask layer 12 are formed on
the growth substrate 10. The growth substrate 10 may be formed, for
example, from one or more of sapphire (Al.sub.2O.sub.3), SiC, Si,
GaAs, ZnO, MgO, GaN, Glass or Ga.sub.2O.sub.3. The mask layer 12
may be formed of the same material as that of the protrusions 11
and may be, for example, formed of one or more of SiO.sub.2, SiN,
GaO, ZnO, or ITO.
[0067] The undoped nitride layer 20 is grown on the growth
substrate 10 on which the mask layer 12 and the protrusions 11 are
formed. A light emitting structure layer 60, including a first
conductivity type semiconductor layer 30, an active layer 40, and a
second conductivity type semiconductor layer 50, is grown on the
undoped nitride layer 20. The undoped nitride layer 20 is grown on
the growth substrate 10 to cover the mask layer 12 and the
protrusions 11 through a horizontal growth and a vertical
growth.
[0068] The first conductivity type semiconductor layer 30 may be
formed, for example, from a GaN-based semiconductor layer including
an n-type impurity such as silicon (Si), and the second
conductivity type semiconductor layer 50 may be formed, for
example, from a GaN-based semiconductor layer including a p-type
impurity such as Mg.
[0069] The active layer 40 may be formed of InGaN layer/GaN layer
having a single quantum well structure or multi-quantum well
structure by supplying ammonia (NH.sub.3), trimethylgallium (TMGa),
and trimethylindium (TMIn).
[0070] Referring to FIG. 13, because the light emitting structure
layer 60 is grown into chip units defined by the mask layer 12, a
spacing exists between the light emitting structure layers 60
adjacent to each other. Therefore, a protective layer 90 may be
formed between the light emitting structure layer 60 and the light
emitting structure layer 60. The protective layer 90 may be formed
of a material such as polyimide or SOG or another material.
[0071] A second electrode 110 is formed on the light emitting
structure layer 60 and the protective layer 90. The second
electrode layer 110 may be formed by first forming an ohmic contact
layer 111, forming a reflective layer 112 on the ohmic contact
layer 111, and forming a conductivity supporting substrate 113 on
the reflective layer 112.
[0072] The conductivity supporting substrate 113 may be formed to
include at least one of copper (Cu), titanium (Ti), molybdenum
(Mo), chromium (Cr), nickel (Ni), aluminum (Al), platinum (Pt),
gold (Au), tungsten (W), or conductivity semiconductor material.
The reflective layer 112 may be formed to include a metal
corresponding to at least one of silver (Ag), aluminum (Al), copper
(Cu), or nickel (Ni) having a high reflectivity. Also, the ohmic
contact layer 111 may be formed of a transparent conductivity
oxide, such as indium tin oxide (ITO), aluminum-doped zinc oxide
(AZO), indium zinc oxide (IZO), antimony tin oxide (ATO), or zinc
indium tin oxide (ZITO).
[0073] Referring to FIG. 14, the growth substrate 10, mask layer
12, protective layer 90, and protrusions 11 are removed. The growth
substrate 10 may be removed using, for example, a laser lift-off
method or a chemical lift-off method. Since the mask layer 12 and
the protrusions 11 are disposed between the growth substrate 10 and
the undoped nitride layer 20, the growth substrate 10 can be easily
separated from the undoped nitride layer 20. That is, since the
mask layer 12 and the protrusions 11 are not strongly bonded to the
undoped nitride layer 20, the more wide the area of the mask layer
12 and the protrusions 11, the easier the separation of the growth
substrate 10.
[0074] As the growth substrate 10 is separated, the protrusions 11
and the mask layer 12 can be easily separated and the protective
layer 90 can be removed by using an etchant. Accordingly upper
grooves 32 and stepped portions 31 are formed in the undoped
nitride layer 20.
[0075] Referring to FIG. 15, the undoped nitride layer 20 is
selectively removed to expose the first conductivity type
semiconductor layer 30, and a first electrode 70 is formed on the
first conductivity type semiconductor layer 30.
[0076] FIG. 18 shows a light emitting device package that includes
any of the aforementioned embodiments of the light emitting device.
Referring to FIG. 18, the light emitting device package 600
includes a package body 300, first and second conductivity layers
310 and 320 mounted on the package body 300, a light emitting
device 200 mounted on the package body 300 and electrically coupled
to the first and second conductivity layers 310 and 320, and a
molding member 500 enclosing the light emitting device 200.
[0077] The package body 300 may be formed to include, for example,
one or more of a silicon material, a synthetic resin material, or a
metallic material and may have an inclined surface around the light
emitting device 200.
[0078] The first conductivity layer 310 and the second conductivity
layer 320 are electrically separated and supply electric power to
the light emitting device 200. Also, the first and second
conductivity layers 310 and 320 may reflect light generated from
the light emitting device 200 to increase light efficiency and may
emit heat generated from the light emitting device 200 to an
outside or external location.
[0079] The light emitting device 200 may be any of the light
emitting devices previously described, and light emitting device
200 may be mounted on the package body 300 or on the first
conductivity layer 310 or the second conductivity layer 320. The
light emitting device 200 may be electrically coupled to the first
conductivity layer 310 and the second conductivity layer 320
through a wire 400.
[0080] When the package of FIG. 18 is formed to include a light
emitting device 200 according to the first or second embodiments,
two wires 400 are used. When the package is formed to include a
light emitting device 200 according to the third or fourth
embodiments, only one wire 400 may be used. Alternatively, in the
case where the light emitting device 200 is connected by a flip
chip method, the wire 400 may not be used at all.
[0081] The molding member 500 may be provided to enclose and
protect the light emitting device 100. A fluorescent material may
be included in the molding member 500 to change the wavelength of
light emitted from the light emitting device 200. Because the light
emitting device package 600 employs a light emitting device 200
having enhanced light efficiency, it follows that light emitting
device package 600 will also demonstrate superior light
efficiency.
[0082] According to one embodiment, the light emitting device
package 600 may include a plurality of light emitting device
packages arrayed onto a substrate. A plurality of optical members,
such as a light guide panel, a prism sheet, a diffusion sheet, a
fluorescent sheet, and/or the like, may be arranged on a path of
light emitted from the light emitting device package 600. The light
emitting device package, substrate, and optical members may
function as a backlight unit or lighting unit, and a lighting
system may include, for example, a backlight unit, a lighting unit,
an indicator unit, a lamp, a streetlamp, etc.
[0083] FIG. 19 shows a disassembled view of a backlight unit 1100
that includes a light emitting device or package according to any
one of the aforementioned embodiment. The backlight unit 1100 may
serve as a lighting system for a variety of applications.
[0084] The backlight unit 1100 may include a bottom frame 1140, a
light guide member 1120 disposed in the bottom frame, and a light
emitting module 1110 disposed on at least one side surface of light
guide member 1120 and/or under light guide member 1120. A
reflective sheet 1130 may be disposed under the light guide member
1120.
[0085] The bottom frame 1140 may be formed in a box shape a top
surface of which is opened such that the light guide member 1120,
the light emitting module 1110 and the reflective sheet 1130 can be
received. The bottom frame 1140 may be formed of a metal or resin
material, but other materials are also possible.
[0086] The light emitting module 1110 may include a substrate 700
and a plurality of light emitting device packages 600 mounted on
the substrate 700. The plurality of light emitting device packages
600 may provide light to the light guide member 1120. In the light
emitting module 1110 according to the current embodiment, it is
illustratively shown that the light emitting device packages 600
are mounted on substrate 700, but in other embodiments the light
emitting devices may be mounted directly on the substrate 700.
[0087] As shown in FIG. 19, the light emitting module 1110 may be
disposed on at least one of inner side surfaces of the bottom frame
1140, and thus may provide light to at least one of the side
surfaces of the light guide member 1120.
[0088] It is also to be understood that the light emitting module
1110 may be disposed under the light guide member 1120 inside the
bottom frame 1140 to provide light toward a bottom surface of the
light guide member 1120. However, the constitution may be modified
according to the specific design requirements of the backlight unit
1100 according to, for example, an intended application.
[0089] The light guide member 1120 may be disposed inside the
bottom frame 1140. The light guide member 1120 may convert the
light provided from the light emitting module to a planar light
source and guide the converted plane light source to a display
panel (not shown).
[0090] The light guide member 1120 may be, for example, a light
guide panel (LGP). The LGP may be formed of, for example, one of
acryl-series resin such as polymethyl metaacrylate (PMMA),
polyethylene terephthlate (PET), poly carbonate (PC), COC, and
polyethylene naphthalate resin.
[0091] An optical sheet 1150 may be disposed on the light guide
member 1120, and may include, for example, at least one of a
diffusion sheet, a light-condensing sheet, a brightness enhancement
sheet and a fluorescent sheet. According to one example, the
optical sheet 1150 may be configured by the diffusion sheet, the
light-condensing sheet, the brightness enhancement sheet and the
fluorescent sheet stacked. In this case, the diffusion sheet 1150
diffuses the light emitted from the light emitting module 1110
uniformly, and the diffused light may be condensed on the display
panel (not shown) by the light-condensing sheet.
[0092] At this time, the light emitted from the light-condensing
sheet is a randomly polarized light, and the brightness enhancement
sheet may increase the polarization of the light emitted from the
light-condensing sheet. The light-condensing sheet may be, for
example, a horizontal and/or vertical prism sheet. Also, the
brightness enhancement sheet may be, for example, a dual brightness
enhancement film. Also, the fluorescent sheet may be a transparent
plate or film including a fluorescent material.
[0093] The reflective sheet 1130 may be disposed under the light
guide member 1120, and may serve to reflect light emitted from the
bottom surface of the light guide member 1120 toward a light
emitting surface of the light guide member 1120. The reflective
sheet 1130 may be formed, for example, of a resin material having
good reflectivity such as PET, PC, or PVC resins or other
materials.
[0094] FIG. 20 shows a lighting unit 1200 that includes any one or
more of the aforementioned embodiments of the light emitting device
or light emitting device package. This lighting unit includes a
case body 1210, a light emitting module 1230 installed in the case
body 1210, and a connection terminal 1220 installed in the case
body 1210 to be supplied with an electric power from an external
power source.
[0095] The case body 1210 may be formed of a material having good
heat shielding characteristic, for example, a metal material or a
resin material.
[0096] The light emitting module 1230 may include a substrate 700,
and at least one light emitting device package 600 mounted on the
substrate 700. In the light emitting module 1230 according to the
current embodiment, it is illustratively shown that the light
emitting device packages 600 are mounted on the substrate 700, but
the light emitting devices according to any of the embodiments
described herein may be mounted directly on the substrate 700.
[0097] The substrate 700 may be an insulator substrate on which a
circuit pattern is printed and may include, for example, a general
printed circuit board (PCB), a metal core PCB, a flexible PCB, a
ceramic PCB, etc. Also, the substrate 700 may be formed of a
material to efficiently reflect light, and a surface thereof may be
formed in a color capable of efficiently reflecting light, for
example, white color, silver color, or the like.
[0098] At least one light emitting device package may be mounted on
the substrate 700. Each of the light emitting device packages 200
may include at least one light emitting diode (LED). The light
emitting diode may include a color LED emitting red, green, blue or
white light, and a UV LED emitting ultraviolet (UV).
[0099] The light emitting module 1230 may have a combination of
several LEDs so as to obtain desired color and luminance. For
example, the light emitting module 1230 may have a combination of a
white LED, a red LED, and a green LED so as to obtain a high color
rendering index (CRI). A fluorescent sheet may be further disposed
on a path of light emitted from the light emitting module 1230. The
fluorescent sheet converts the wavelength of the light emitted from
the light emitting module.
[0100] For example, when the light emitted from the light emitting
module 1230 has a blue wavelength band, the fluorescent sheet may
include a yellow fluorescent material, so that the light, which is
emitted from the light emitting module 1230 and passes through the
fluorescent sheet, finally appears as white light.
[0101] The connection terminal 1220 may be electrically coupled to
the light emitting module 1230 to supply an electric power to the
light emitting module 1230. As shown in FIG. 19, the connection
terminal 1220 may be screwed and coupled to an external power, but
the invention is not limited thereto. For example, the connection
terminal 1220 may be made in a pin type and inserted into an
external power, or may be connected to the external power through a
power line.
[0102] As described above, the lighting system may include at least
one of a light guide member, a diffusion sheet, a light-condensing
sheet, a brightness enhancement sheet and a fluorescent sheet on a
traveling path of light to obtain a desired optical effect. Because
the lighting system includes a light emitting device or package
having superior light efficiency, the lighting system can show
superior light efficiency as well.
[0103] One or more embodiments described herein, thus, provide a
light emitting device having a novel structure and a method of
manufacturing the same. One or more of these embodiments also
provide a light emitting device with enhanced light efficiency, and
a method of manufacturing the same. One or more of these
embodiments, also provide a light emitting device and a method of
manufacturing the same in which a growth substrate can be easily
separated.
[0104] In one embodiment, a light emitting device comprises: a
first semiconductor layer; a second semiconductor layer; and an
active layer between the first and second semiconductor layers, the
first semiconductor layer includes a first surface facing the
active layer, and a second surface oppositely facing the first
surface, and the first semiconductor layer has a stepped portion
formed at a side surface thereof and thus the area of the second
surface is smaller than a maximum area of the first semiconductor
layer.
[0105] In another embodiment, a light emitting device package
comprises: a package body; a first conductivity layer and a second
conductivity layer on the package body; a light emitting device
disposed on the package body and electrically connected to the
first conductivity layer and the second conductivity layer; and a
molding member enclosing the light emitting device, wherein the
light emitting device includes a first semiconductor layer, a
second semiconductor layer, and an active layer between the first
semiconductor layer and the second semiconductor layer, the first
semiconductor layer includes a first surface facing the active
layer, and a second surface oppositely facing the first surface,
and the first semiconductor layer has a stepped portion formed at a
side surface thereof and thus the area of the second surface is
smaller than a maximum area of the first semiconductor layer.
[0106] In a further embodiment, a lighting system comprises: a
light emitting module including a substrate; and a light emitting
device on the substrate, wherein the light emitting device
comprises: a first semiconductor layer; a second semiconductor
layer; and an active layer between the first semiconductor layer
and the second semiconductor layer, the first semiconductor layer
includes a first surface facing the active layer, and a second
surface oppositely facing the first surface, and the first
semiconductor layer has a stepped portion formed at a side surface
thereof and thus the area of the second surface is smaller than a
maximum area of the first semiconductor layer.
[0107] In still another embodiment, a method of manufacturing a
light emitting device, comprises: forming a mask layer defining a
plurality of light emitting structure layer growth regions on a
growth substrate; forming a light emitting structure layer
including a first conductivity type semiconductor layer, an active
layer and a second conductivity type semiconductor layer from the
light emitting structure layer growth regions; selectively removing
the light emitting structure layer and forming a first electrode on
the first conductivity type semiconductor layer and a second
electrode on the second conductivity type semiconductor layer; and
cutting the growth substrate and the mask layer to separate the
growth substrate and the light emitting structure layer.
[0108] In yet another embodiment, a method of manufacturing a light
emitting device, comprises: forming a mask layer defining a
plurality of light emitting structure layer growth regions on a
growth substrate; forming a light emitting structure layer
including a first conductivity type semiconductor layer, an active
layer and a second conductivity type semiconductor layer from the
light emitting structure layer growth regions; forming a protective
layer between the light emitting structure layers; forming a second
electrode on the light emitting structure layer and the protective
layer; separating the growth substrate and removing the mask layer
and the protective layer; forming a first electrode on the first
conductivity type semiconductor layer; and cutting the second
electrode to separate the second electrode and the light emitting
structure layer.
[0109] In accordance with another embodiment, a light emitting
device comprises a first semiconductor layer; a second
semiconductor layer; and an active layer between the first and
second semiconductor layers, wherein the first semiconductor layer
includes a first surface facing the active layer, a second surface
opposing the first surface, and a side surface that includes a
stepped portion. The stepped portion causes the side surface to
extend beyond one of the first surface or second surface.
[0110] The area of the first surface may be greater than an area of
the second surface, the area of the second surface may be less than
the area of the first surface as a result of the stepped portion,
or an area of the first surface may be less than an area of the
second surface. In addition, the first semiconductor layer is a
first conductivity type and the second semiconductor layer is a
second conductivity type.
[0111] The device may also include a buffer layer, wherein a first
semiconductor layer is located between the buffer layer and active
layer, the first semiconductor layer is of a first conductivity
type, and the second semiconductor layer is of a second
conductivity type. The buffer layer may be on a first portion of
the first conductivity type semiconductor, and the device may
further comprise a first electrode on the first semiconductor layer
where the buffer layer is not formed and a second electrode under
the second semiconductor layer.
[0112] The buffer layer may be divided into first and second
sections disposed on the first semiconductor layer, the first and
second sections of the buffer layer separated to expose a portion
of the first semiconductor layer, the first electrode electrically
coupled to the exposed portion of the first semiconductor layer.
The buffer layer may be an undoped layer or a doped layer, and if
undoped may include a nitride.
[0113] The device may further include at least one reflector to
reflect light emitted from the active layer. The reflector is
located adjacent the first semiconductor layer, and may be formed
as a protrusion that extends from a surface of a substrate that
supports or is coupled to the first semiconductor layer.
[0114] The device may also include at least one diffuser, located
on the second surface of the first semiconductor layer, to diffuse
light emitted from the active layer. The diffuser may extend into
the second surface of the first semiconductor layer, and may
include a recess that extends into the second surface of the first
semiconductor layer.
[0115] In accordance with another embodiment, a light emitting
device comprises a buffer layer, a first semiconductor layer, a
second semiconductor layer, and an active layer between the first
and second semiconductor layers. The first semiconductor layer is
between the buffer layer and active layer, the active layer is
between the first and second semiconductor layers, and a bottom
surface of the buffer layer has an area smaller than an area of at
least one of the surfaces of the first semiconductor layer.
[0116] Additionally, a side surface of the buffer layer may
includes a stepped portion which causes a top surface of the buffer
layer facing the first semiconductor layer to have an area greater
than the bottom surface of the buffer layer.
[0117] Additionally, a side surface of the buffer layer may
includes a stepped portion which causes the side surface of the
buffer layer to extend beyond at least one of a top surface or the
bottom surface of the buffer layer. The buffer layer may be a doped
layer or an undoped layer.
[0118] In addition, the device may include at least one reflector
to reflect light emitted from the active layer. The reflector may
be adjacent the buffer layer and may include a protrusion that
extends from a surface of a substrate that supports or is coupled
to the buffer layer.
[0119] A light emitting device package may be formed to comprise a
light emitting device in accordance with any one of the
aforementioned embodiments.
[0120] In accordance with another embodiment, a lighting system
comprises a light emitting device as recited in claim 1, wherein
said device is coupled to a substrate of a light emitting
module.
[0121] In accordance with another embodiment, a method of
manufacturing a light emitting device comprises forming a mask
layer on a substrate to define a region of a light emitting device;
forming a semiconductor layer of a first conductivity type, an
active layer, and a semiconductor layer of a second conductivity
type at said region; selectively removing the mask layer; and
forming first and second electrodes electrically coupled to the
first and second semiconductor layers respectively, wherein one of
the semiconductor layers is formed to include a first surface
facing the active layer, a second surface opposing the first
surface, and a side surface that includes a stepped portion, and
wherein the stepped portion causes the side surface to extend
beyond one of the first surface or second surface.
[0122] In accordance with another embodiment, a method of
manufacturing a light emitting device, comprises forming a mask
layer on a substrate to define a region of a light emitting device;
forming a semiconductor layer of a first conductivity type, an
active layer, and a semiconductor layer of a second conductivity
type at said region; selectively removing the mask layer; and
forming first and second electrodes electrically coupled to the
first and second semiconductor layers respectively, wherein one of
the semiconductor layers is formed to include a first surface
facing the active layer.
[0123] The method further includes forming a buffer layer coupled
to the first and second semiconductor layers and the active layer,
wherein a bottom surface of the buffer layer has an area smaller
than an area of at least one of the surfaces of the semiconductor
layer of the first conductivity type or the second conductivity
type. Also, buffer layer may include a stepped portion that causes
the bottom surface of the buffer layer to have an area smaller than
an area of at least one of the surfaces of the semiconductor layer
of the first conductivity type or the second conductivity type.
[0124] Herein, when a layer (or film) is referred to as being "on"
another layer or substrate, it understood that it can be directly
on the other layer or substrate, or that intervening layers may be
present between them. Further, it will be understood that when a
layer is referred to as being "under" another layer, it can be
directly under the other layer, and or that one or more intervening
layers may be present. In addition, it is to be understood that
when a layer is referred to as being "between" two layers, that
layer may be the only one between the two layers or one or more
intervening layers may also be present between them.
[0125] In the figures, the dimensions of layers and regions are
exaggerated for clarity of illustration. In addition, the dimension
of each part does not reflect an actual size.
[0126] 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.
[0127] 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.
* * * * *