Light emitting diode and manufacturing method thereof

A light emitting diode includes a support substrate; a light emitting structure including a second semiconductor layer, an active layer, and a first semiconductor layer; at least one groove formed on the lower surface of the light emitting structure; a second electrode located on at least the lower surface of the second semiconductor layer, and electrically connected with the second semiconductor layer; an insulating layer partially covering the second electrode and the lower surface of the light emitting structure, and including at least one opening corresponding to the at least one groove; and a first electrode electrically connected to the first semiconductor layer exposed to the at least one groove, and at least partially covering the insulating layer, wherein the second electrode includes a second contact layer including an ohmic contact layer, and the ohmic contact layer is disposed in the shape of a plurality of islands.

CROSS REFERENCE TO RELATED APPLICATION

This application is the National Stage Entry of International Application No. PCT/KR2015/008839, filed on Aug. 24, 2015, and claims priority from Korean Patent Application No. 10-2014-0112448, filed on Aug. 27, 2014 and Korean Patent Application No. 10-2015-0116053, filed on Aug. 18, 2015, each of which is incorporated herein by reference for all purposes as if fully set forth herein.

BACKGROUND

Field

Exemplary embodiments of the present disclosure relate to a light emitting diode and a method of manufacturing the same, and more particularly, to a light emitting diode that has low contact resistance between a semiconductor layer having a non-polar or semi-polar growth plane and an electrode, and a method of manufacturing the same.

Discussion of the Background

Recently, with increasing demand for high output light emitting diodes, there is increasing demand for vertical light emitting diodes having good heat dissipation efficiency and luminous efficacy. For a vertical light emitting diode, a growth substrate is separated from semiconductor layers to improve light extraction efficiency by increasing roughness of a separated surface and a metal substrate is attached to an overall upper surface of a P-type semiconductor layer in order to improve heat dissipation efficiency. With this structure, the vertical type light emitting diode can be applied to high output light emitting diodes driven at high current density.

Generally, a light exit surface of the vertical type light emitting diode is present on one surface of an n-type semiconductor layer exposed due to separation of the growth substrate. A surface of the p-type semiconductor layer opposite the light exit surface is formed with components for reflecting light, for example, a reflective electrode layer such as an Ag layer. Japanese Unexamined Patent Publication No. 2010-56423 discloses a technology in which heat treatment is performed in order to reduce contact resistance of the Ag layer while maintaining reflection characteristics thereof.

Recently, output and reliability requirements of light emitting diodes used in various applications are much higher than those of typical light emitting diodes. Accordingly, research and development of techniques for manufacturing a vertical light emitting diode by growing nitride semiconductor layers on a growth substrate having a non-polar or semi-polar growth plane are actively conducted. Such vertical light emitting diodes having nonpolar or semi-polar growth planes exhibit low efficiency drooping compared with light emitting diodes having polar growth planes and thus are suitable for high power light emitting diodes.

However, in a nitride semiconductor layer grown on such a nonpolar or semi-polar growth plane, contact resistance of a reflective electrode including a P-type semiconductor layer and Ag is much higher than that of a nitride semiconductor layer grown on the C-plane. Moreover, when heat treatment disclosed in Japanese Unexamined Patent Publication No 2010-56423 and the like is performed on the reflective electrode in order to lower contact resistance, reflection characteristics are deteriorated, thereby causing significant deterioration in luminous efficacy of the light emitting diode.

SUMMARY

Exemplary embodiments of the present disclosure provide a light emitting diode that includes a contact electrode having improved electrical and optical characteristics, and a method of manufacturing the same.

In accordance with one aspect of the present disclosure, a light emitting diode includes: a support substrate; a light emitting structure disposed on the support substrate and having a non-polar or semi-polar growth plane, the light emitting structure including a second conductive type semiconductor layer, an active layer disposed on the second conductive type semiconductor layer, and a first conductive type semiconductor layer disposed on the active layer; at least one groove formed on a lower surface of the light emitting structure and partially exposing the first conductive type semiconductor layer; a second type electrode disposed at least on a lower surface of the second conductive type semiconductor layer and electrically connected to the second conductive type semiconductor layer; an insulation layer partially covering the second type electrode and the lower surface of the light emitting structure, and including at least one opening corresponding to the at least one groove; and a first type electrode electrically connected to the first conductive type semiconductor layer exposed to the groove and at least partially covering the insulation layer, wherein the second type electrode includes a second type contact layer contacting the second conductive type semiconductor layer, and the second type contact layer includes an ohmic contact layer, the ohmic contact layer being composed of a plurality of regular or irregular islands.

With this structure, the light emitting diode can have low contact resistance between the electrode and the semiconductor layer and can provide good luminous efficacy.

The ohmic contact layer may include at least one material selected from the group consisting of Ni, Pt, Mg, Ni/Au, and a conductive oxide.

The second type contact layer may further include a reflective layer covering the ohmic contact layer, and the reflective layer may include Ag and/or Al.

The second type electrode may further include a second type barrier layer at least partially covering the second type contact layer, and a portion of the second type barrier layer may extend from one side surface of the light emitting structure to be exposed at an upper surface thereof.

Some portion of a lower surface of the second type contact layer may be covered by the second type barrier layer and the other portion of the lower surface of the second type contact layer may be covered by the insulation layer.

At least part of the portion of the insulation layer covering the lower surface of the second type contact layer may be interposed between the second type barrier layer and the second type contact layer.

The light emitting diode may further include a second type pad electrode electrically connected to the second type barrier layer and formed in a region to which the upper surface of the second type barrier layer is exposed, and a lower surface of the second type pad electrode may at least partially contact the second type barrier layer.

The first type electrode may include a first type contact layer contacting the first conductive type semiconductor layer and a first type barrier layer at least partially covering the first type contact layer.

The first type contact layer may cover a lower surface of the insulation layer.

The first type contact layer may fill the at least one opening and may not be disposed on the lower surface of the second conductive type semiconductor layer.

The light emitting diode may further include a bonding layer bonding the support substrate to the second type electrode.

In accordance with another aspect of the present disclosure, a method of manufacturing a light emitting diode may include: forming a light emitting structure on a growth substrate having a non-polar or semi-polar growth plane, the light emitting structure including a first conductive type semiconductor layer, an active layer disposed on the first conductive type semiconductor layer, and a second conductive type semiconductor layer disposed on the active layer; removing a portion of the light emitting structure so as to form at least one groove partially exposing the first conductive type semiconductor layer, while forming a second type electrode on the second conductive type semiconductor layer; forming an insulation layer covering the light emitting structure and the second type electrode and including at least one opening corresponding to the groove; forming a first type electrode electrically connected to the first conductive type semiconductor layer through the opening and at least partially covering the insulation layer; forming a support substrate on the first type electrode; and separating the growth substrate from the light emitting structure, wherein forming the second type electrode includes forming a second type contact layer including an ohmic contact layer, and the ohmic contact layer contacts the second conductive type semiconductor layer and is formed in a pattern of a plurality of regular or irregular islands through deposition and/or patterning.

The ohmic contact layer may include at least one material selected from the group consisting of Ni, Pt, Mg, Au/Ni, and a conductive oxide.

Forming the second type contact layer may further include forming a reflective layer covering the ohmic contact layer, and the reflective layer may include Ag and/or Al.

Forming the second type electrode may further include a second type barrier layer at least partially covering the second type contact layer.

The method of manufacturing a light emitting diode may further include partially removing the light emitting structure so as to expose a portion of the second type barrier layer after separation of the growth substrate.

The method of manufacturing a light emitting diode may further include forming a second type pad electrode on at least some portion in a region, to which the second type barrier layer is partially exposed, so as to be electrically connected to the second type barrier layer.

Forming the first type electrode may include forming a first type contact layer filling the opening while at least partially covering the insulation layer; and forming a first type barrier layer on the first type contact layer.

The method of manufacturing a light emitting diode may further include forming a bonding layer on the second type electrode to bond the support substrate to the second type electrode, before separation of the growth substrate.

The method of manufacturing a light emitting diode may further include forming a roughness on a surface of the first conductive type semiconductor layer exposed by separation of the growth substrate, and forming the roughness may be performed using dry etching.

In accordance with a further aspect of the present disclosure, a light emitting diode includes: a light emitting structure including a first conductive type semiconductor layer, a second conductive type semiconductor layer, and an active layer interposed between the first conductive type semiconductor layer and the second conductive type semiconductor layer, the light emitting structure having at least one groove formed through the second conductive type semiconductor layer and the active layer to expose a portion of the first conductive type semiconductor layer, the light emitting structure having a non-polar or semi-polar growth plane; a first type electrode and a second type electrode disposed on the light emitting structure and forming ohmic contact with the first and second conductive type semiconductor layers, respectively; an insulation layer insulating the first type electrode and the second type electrode from each other, and including a first opening and a second opening exposing the first type electrode and the second type electrode, respectively; and a first electrode pad and a second electrode pad disposed on the insulation layer and electrically connected to the first type electrode and the second type electrode, respectively, wherein the second type electrode includes a second type contact layer contacting the second conductive type semiconductor layer, the second type contact layer includes an ohmic contact layer, and the ohmic contact layer is formed in a pattern of a plurality of regular or irregular islands.

The ohmic contact layer may include at least one material selected from the group consisting of Ni, Pt, Mg, Ni/Au, and a conductive oxide.

The second type contact layer may further include a reflective layer covering the ohmic contact layer, and the reflective layer may include Ag and/or Al.

The light emitting structure may include a plurality of grooves and the second opening may not be disposed above the plurality of grooves.

According to exemplary embodiments of the present disclosure, the light emitting diode has a non-polar or semi-polar growth plane to secure low forward voltage by securing low contact resistance between a second type electrode and a second conductive type semiconductor layer while securing good luminous efficacy.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so as to fully convey the spirit of the present disclosure to those skilled in the art to which the present disclosure pertains. Accordingly, the present disclosure is not limited to the embodiments disclosed herein and can also be implemented in different forms. In the drawings, widths, lengths, thicknesses, and the like of elements can be exaggerated for clarity and descriptive purposes. When an element is referred to as being “disposed above” or “disposed on” another element, it can be directly “disposed above” or “disposed on” the other element, or intervening elements can be present. Throughout the specification, like reference numerals denote like elements having the same or similar functions.

FIG. 1is a plan view of a light emitting diode according to one exemplary embodiment of the present disclosure.FIG. 2Ais a cross-sectional view taken along line X-X ofFIG. 1. In addition,FIG. 2Bis a cross-sectional view taken along line X-X ofFIG. 1showing regions A, B, and C. Region A ofFIG. 2Bcorresponds to enlarged sectional views ofFIGS. 3A, 3B, 3C, 4A, 4B, and 4C. Region B ofFIG. 2Bcorresponds to enlarged sectional views ofFIGS. 5A and 5B. Region C ofFIG. 2Bcorresponds to enlarged sectional views ofFIGS. 6A and 6B.

Referring toFIG. 1andFIG. 2, a light emitting diode according to one exemplary embodiment includes a light emitting structure120, at least one groove120h, a first type electrode130, a second type electrode140, and an insulation layer150. The light emitting diode may further include a bonding layer160, a support substrate171, a second type pad electrode173, and a passivation layer180.

The light emitting structure120may include a first conductive type semiconductor layer121, an active layer123, and a second conductive type semiconductor layer125, in which the first conductive type semiconductor layer121is disposed on the second conductive type semiconductor layer125and the active layer123is interposed between the first and second conductive type semiconductor layers121,125. The light emitting structure120may further include a roughness120R formed on an upper surface thereof.

The first conductive type semiconductor layer121and the second conductive type semiconductor layer125may include a Group III-V compound semiconductor, for example, a nitride semiconductor such as (Al, Ga, In)N. The first conductive type semiconductor layer121may include an n-type semiconductor layer doped with n-type dopants (for example, Si) and the second conductive type semiconductor layer125may include a p-type semiconductor layer doped with p-type dopants (for example, Mg), or vice versa. Furthermore, the first conductive type semiconductor layer121and/or the second conductive type semiconductor layer125may be composed of a single layer or multiple layers. For example, the first conductive type semiconductor layer121and/or the second conductive type semiconductor layer125may include a clad layer and a contact layer, and may include super-lattice layers.

The active layer123may include a multi-quantum well (MQW) structure, and elements and composition of the multi-quantum well structure can be adjusted to allow the multi-quantum well structure to emit light having a desired peak wavelength. For example, well layers of the active layer123may be ternary semiconductor layers such as InxGa(1-x)N (0≤≤x≤≤1) or quaternary semiconductor layers such as AlxInyGa(1-x-y)N(0≤≤x≤≤1, 0≤≤y≤1, 0≤≤x+y≤≤1), and the value of x or y may be adjusted in order to allow the active layer to emit light having a desired wavelength. It should be understood that other implementations are also possible.

The light emitting structure120may be grown on the growth substrate having a non-polar or semi-polar growth plane. Thus, the light emitting structure120including the first conductive type semiconductor layer121, the active layer123and the second conductive type semiconductor layer125may have a non-polar or semi-polar growth plane. The non-polar growth plane may include the m-plane or the a-plane.

A surface of the light emitting structure120, that is, an upper surface of the first conductive type semiconductor layer121, may be formed with a roughness120R. The roughness120R may be formed by performing surface treatment on the surface of the first conductive type semiconductor layer121using at least one of various methods such as dry etching, wet etching, and electro-chemical etching. With the roughness120R, the light emitting diode can improve extraction efficiency of light emitted through an upper surface thereof.

At least one groove120hmay be formed on a lower surface of the light emitting structure120and may be formed in plural, as shown in the drawings. The at least one groove120hmay be formed by removing some regions of the lower surface of the light emitting structure120, and the first conductive type semiconductor layer121may be exposed through the groove120h. Further, the second conductive type semiconductor layer125and the active layer123may be exposed to a side surface of the groove120h, and the side surface of the groove120hmay be an inclined side surface. Since the grooves120hhave an inclined side surface, the first type electrode130and the insulation layer150disposed on the side surface of the groove120hcan have improved step coverage characteristics.

When the groove120his composed of a plurality of grooves, the shape of the grooves120hmay be modified in various ways. As described below, since the first type electrode130is electrically connected to the first conductive type semiconductor layer121through the grooves120h, the arrangement of the grooves120hmay be modified in various ways in consideration of current dispersion and density of electric current upon driving of the light emitting diode. For example, the grooves120hmay be arranged in the form of plural dots, plural stripes, or combinations thereof. However, it should be understood that other implementations are also possible.

The second type electrode140may be disposed at least on a lower surface of the second conductive type semiconductor layer125and may be electrically connected to the second conductive type semiconductor layer125, and some the second type electrode140may extend from a side surface of the light emitting structure120such that an upper surface thereof can be exposed. In addition, the second type electrode140may include a second type contact layer141and a second type barrier layer143.

The second type contact layer141is disposed on the lower surface of the second conductive type semiconductor layer125, whereby the second type contact layer141can form ohmic contact with the second conductive type semiconductor layer125. In addition, the second type contact layer141may include an ohmic contact layer and a reflective layer covering the ohmic contact layer. When the second conductive type semiconductor layer125is a p-type semiconductor layer, the ohmic contact layer may include a material that forms ohmic contact with the second conductive type semiconductor layer125having a non-polar or semi-polar growth plane, and the reflective layer may have light reflectivity and may also include a material that forms ohmic contact with the second conductive type semiconductor layer125.

Here, contact resistance between the ohmic contact layer and the second conductive type semiconductor layer125may be lower than the contact resistance between the reflective layer and the second conductive type semiconductor layer125. Accordingly, the contact resistance between the second type electrode140and the second conductive type semiconductor layer125can be lowered. In this regard, various exemplary embodiments of the present disclosure will now be described in detail with reference toFIG. 3AandFIG. 3B.

FIG. 3Ais an enlarged sectional view of a second type contact layer according to exemplary embodiments of the present disclosure.FIG. 3Bis a plan view of the second type contact layer ofFIG. 3A.FIG. 3Cis an enlarged sectional view of a second type contact layer according to exemplary embodiments of the present disclosure.FIG. 3Dis a plan view of the second type contact layer ofFIG. 3C.FIG. 3Eis an enlarged sectional view of a second type contact layer according to exemplary embodiments of the present disclosure.FIG. 3Fis a plan view of the second type contact layer ofFIG. 3E.FIGS. 3A, 3C, and 3Eare each a sectional view of Region A ofFIG. 2B.FIGS. 3B, 3D, and 3Fare each a schematic plan view of a portion of the second type contact layer141.

First, referring toFIGS. 3A and 3B, the second type contact layer141may include an ohmic contact layer1411and a reflective layer1413covering the ohmic contact layer1411.

The ohmic contact layer1411forms ohmic contact with the second conductive type semiconductor layer125having a non-polar or semi-polar growth plane, and may include a material having low contact resistance. For example, the ohmic contact layer1411may include a material selected from the group consisting of Ni, Pt, Mg, Ni/Au, a conductive oxide, and some combination thereof. The conductive oxide may include ITO, IZO, IZTO, IAZO, IGZO, IGTO, AZO, IrOx, RuOx, RuOx/ITO, MgO, ZnO, and the like. In addition, the ohmic contact layer1411may be formed in a pattern of plural regular islands, as shown in the drawings. Here, the ohmic contact layer1411of each island may have a semi-spherical shape.

However, it should be understood that other implementations are also possible. Alternatively, the ohmic contact layer may have a different shape from the shape shown inFIGS. 3C, 3D, 3E, and 3F. As shown inFIGS. 3C and 3D, the ohmic contact layer1411amay have a pattern of a plurality of irregular islands, each of which may have a different shape and size than other islands. Alternatively, as shown inFIGS. 3E and 3F, the ohmic contact layer1411bmay be formed in the form of a monolithic film.

The reflective layer1413may be formed to cover the ohmic contact layer1411and at least part of the reflective layer1413may contact the second conductive type semiconductor layer125. The reflective layer1413may include a material, for example, Ag and/or Al, which has high reflectivity with respect to light, exhibits electrical conductivity, and can form ohmic contact with the second conductive type semiconductor layer125. The reflective layer1413is formed on the lower surface of the second conductive type semiconductor layer125, whereby light emitted from the light emitting structure120can be reflected toward an upper side of the light emitting diode, thereby improving luminous efficacy of the light emitting diode.

According to exemplary embodiments, the ohmic contact layer1411interposed between the reflective layer1413and the second conductive type semiconductor layer125may be formed to reduce contact resistance between the second electrode140and the second conductive type semiconductor layer125. In addition, as compared with a structure where only the reflective layer1413is provided, the ohmic contact layer1411relatively reduces a contact area between the reflective layer1413and the second conductive type semiconductor layer125. Thus, even without reducing the contact resistance between the reflective layer1413and the second conductive type semiconductor layer125as in the related art, the forward voltage Vf of the light emitting diode can be reduced by lowering the contact resistance between the second type contact layer141and the second conductive type semiconductor layer125. Furthermore, since the ohmic contact layer1411allows heat treatment to be performed at low temperature or to be omitted in order to reduce the contact resistance of the reflective layer1413, it is possible to prevent a decrease in reflectance of the reflective layer1413due to heat treatment.

Referring again toFIG. 1andFIGS. 2A and 2B, the second type barrier layer143is disposed on the lower surface of the second conductive type semiconductor layer125and may at least partially cover the second type contact layer141. In addition, the second type barrier layer143may be integrally formed under a region excluding the at least one groove120h. Further, a portion of the second type barrier layer143may extend from a side surface of the light emitting structure120so as to be exposed, instead of being disposed under the light emitting structure120.

The second type barrier layer143can prevent diffusion between the second type contact layer141and other materials. Accordingly, it is possible to prevent the second type contact layer141from suffering from reflectance deterioration and resistance increase due to diffusion of other materials into the second type contact layer141. In addition, the second type barrier layer143may act as a secondary light reflector. That is, when some of light traveling towards a region at which the second type contact layer141is not formed is directed to a region at which the second type barrier layer143is disposed, the second type barrier layer143may also reflect the light. Accordingly, the second type barrier layer143can prevent foreign impurities from penetrating into the second type contact layer141and may include a material having light reflectivity. The second type barrier layer143may include at least one material selected from the group consisting of Au, Ni, Ti, W, Pt, Cu, Pd, Ta, and Cr. The second type barrier layer143may be composed of a single layer or multiple layers.

The second type barrier layer143may cover the second type contact layer141in various shapes, which will not be described together with various exemplary embodiments with reference toFIG. 4A,FIG. 4B, andFIG. 4C.

FIG. 4A,FIG. 4B, andFIG. 4Care enlarged sectional views a second type barrier layer according to exemplary embodiments of the present disclosure.FIG. 4A,FIG. 4B, andFIG. 4Care each a sectional view of Region A ofFIG. 2B.

First, referring toFIG. 4A, the second type barrier layer143may completely cover the second type contact layer141, as shown inFIG. 2B. Thus, a portion of the second type contact layer141may contact the second conductive type semiconductor layer125.

Next, referring toFIG. 4B, the second type barrier layer143amay be disposed only on some portion of a lower surface of the second type contact layer141, whereby some portion of the second type contact layer141may be covered by the insulation layer150described below. In this exemplary embodiment, the second type barrier layer143aand the insulation layer150prevent external impurities from diffusing into the second type contact layer141. According to this exemplary embodiment, it is possible to prevent the second type barrier layer143afrom being peeled off due to deterioration in adhesion at a contact portion between the second type barrier layer143aand the second conductive type semiconductor layer125. As such, this structure prevents the second type barrier layer143afrom being peeled off, thereby more effectively preventing external impurities from penetrating into the second type contact layer141at an interface between the second conductive type semiconductor layer125and the second type barrier layer143a.

Referring again toFIG. 4C, the second type barrier layer143bcovers some portion of the lower surface of the second type contact layer141and other portions of the lower surface of the second type contact layer141not covered by the second type barrier layer143bmay be covered by the insulation layer150. In addition, the second type barrier layer143bmay further cover the insulation layer150such that at least some portion of the insulation layer150covering the second type contact layer141may be interposed between the second type contact layer141and the second type barrier layer143b. That is, the second type barrier layer143band the insulation layer150may be formed to mesh with each other. As such, since the second type barrier layer143bis fitted into the insulation layer150, this structure can more effectively prevent external impurities from penetrating into the second type contact layer141due to peeling off of the second type barrier layer143b.

Referring again toFIG. 1andFIGS. 2A and 2B, a portion of the second type barrier layer143may extend from the side surface of the light emitting structure120to be exposed and the exposed portion of the second type barrier layer143may be electrically connected to the second type pad electrode173. This structure will be described in detail below.

The insulation layer150may be disposed under the light emitting structure120and may cover the second type electrode140. In addition, the insulation layer150may cover the side surface of the groove120hand may include at least one opening placed corresponding to the groove120hso as to expose a portion of the first conductive type semiconductor layer121. Accordingly, a portion of a lower surface of the first conductive type semiconductor layer121can be exposed through the opening without being covered by the insulation layer150.

The insulation layer150may be interposed between the first type electrode130and the second type electrode140, and may insulate the first type and second type electrodes130,140from each other. Accordingly, the insulation layer150may include an insulating material, for example, SiO2or SiNx. Furthermore, the insulation layer150may be composed of multiple layers and may include a distributed Bragg reflector in which materials having different indices of refraction are alternately stacked one above another. In the structure wherein the insulation layer150includes a distributed Bragg reflector, light directed to a lower side of the light emitting diode is more effectively reflected, thereby further improving luminous efficacy of the light emitting diode.

The first type electrode130may be disposed under the insulation layer150and the light emitting structure120, and may cover a lower surface of the insulation layer150. The first electrode130may be electrically connected to the first conductive type semiconductor layer121through the opening of the insulation layer150disposed corresponding to the groove120h.

The first type electrode130may include a first type contact layer131and a first type barrier layer133, which may at least partially cover the first type contact layer131. In this structure, as shown inFIGS. 2A and 2B, the first type contact layer131may be interposed between the first type barrier layer133and the insulation layer150, and the first type contact layer131may contact the first conductive type semiconductor layer121through the opening of the insulation layer150. The first type barrier layer133is formed to at least partially cover the first type contact layer131, thereby preventing diffusion of some impurities from the bonding layer160to the first type contact layer131.

The following description is given of the shape and arrangement of the first type contact layer131according to some exemplary embodiments with reference toFIG. 5AandFIG. 5B.FIG. 5AandFIG. 5Bare enlarged sectional views showing contact between the first conductive type semiconductor layer121and the first type electrode130according to exemplary embodiments of the present disclosure.FIG. 5AandFIG. 5Bare enlarged sectional views of Region B ofFIG. 2B.

First, referring toFIG. 5A, the first type contact layer131may be formed to cover the lower surface of the insulation layer150, as shown inFIGS. 2A and 2B, and may cover the insulation layer150formed on the side surface of the groove120h. In addition, the first type contact layer131may fill the opening of the insulation layer150disposed corresponding to the groove120hto contact the first conductive type semiconductor layer121. Accordingly, the first type barrier layer133does not directly contact the insulation layer150. In this structure, the first type contact layer131may also act to reflect light. For example, the first type contact layer131may reflect light, which is emitted from the light emitting structure120and is directed towards the surface of the groove120hinstead of being directed towards the second type electrode140, in an upward direction.

Alternatively, as shown inFIG. 5B, the first type contact layer131amay be formed at a location of the groove120hto contact the first conductive type semiconductor layer121by filling the opening of the insulation layer150and may not be disposed on the lower surface of the second conductive type semiconductor layer125. That is, the first type contact layer131afills the opening of the insulation layer150to form ohmic contact with the first conductive type semiconductor layer121to electrically connect the first type barrier layer133and the first conductive type semiconductor layer121. At this time, the first type barrier layer133may cover the first type contact layer131aand the lower surface of the insulation layer150. Accordingly, in this exemplary embodiment, light, which is emitted from the light emitting structure120and directed towards the surface of the groove120hinstead of being directed towards the second type electrode140, may be reflected upward through the first type barrier layer133.

It should be understood that the first type electrode130according to the present disclosure is not limited thereto.

As described above, the first type contact layer131may form ohmic contact with the first conductive type semiconductor layer121and may also act to reflect light. Accordingly, the first type contact layer131may be composed of a single layer or multiple layers. The first type contact layer131may include at least one stack structure of the group consisting of Ti/Al, Ni/Al, Cr/Al, and Pt/Al. The first type contact layer131may further include Ni, W, Pt, Cu, Ti, Pd, Ta, Au and the like in order to prevent aggregation of Al. In addition, the first type contact layer131may include a conductive oxide such as ITO.

The first type barrier layer133can prevent external impurities from diffusing into the first type contact layer131, and may be electrically connected to the first type contact layer131and may also act to reflect light. Accordingly, the first type barrier layer133may be composed of a single layer or multiple layers, and may include Ni, W, Pt, Cu, Ti, Pd, Ta, Au, and the like.

The support substrate171may be disposed under the light emitting structure120and may be bonded to the first type electrode130through the bonding layer160. The support substrate171may be a conductive substrate, a circuit substrate, or an insulating substrate having a conductive pattern formed thereon. In this exemplary embodiment, the supporting substrate171may be a metal substrate and may include, for example, a structure in which a Mo layer and a Cu layer are stacked. The support substrate171may include Ti, Cr, Ni, Al, Cu, Ag, Au, Pt, and the like.

The support substrate171may be electrically connected to the first type electrode130to act as a first type pad electrode that supplies external power to the first conductive type semiconductor layer121of the light emitting structure120. For example, when the light emitting diode according to this exemplary embodiment is applied to various applications, the support substrate171is electrically connected to a structure such as an external lead electrode, thereby providing an electric path for supplying external power to the light emitting diode.

The bonding layer160is interposed between the first type electrode130and the support substrate171to bond the first type electrode130and the support substrate171. The bonding layer160may include a conductive material and may include a material, such as AuSn, NiSn, InSn, NiAu, InAu, CuSn, and the like. For example, when the bonding layer160includes AuSn, Au and Sn can form a eutectic structure through eutectic bonding.

The second type pad electrode173may be spaced apart from the side surface of the light emitting structure120and may be disposed on a region to which the second type barrier layer143is exposed.

At least part of a lower surface of the second type pad electrode173may contact the second type barrier layer143to be electrically connected thereto. For example, as shown inFIG. 6A, the entire lower surface of the second type pad electrode173may contact the second type barrier layer143. Alternatively, only a portion of the lower surface of the second type pad electrode173may contact the second type barrier layer143c, and the remaining portion thereof may contact the insulation layer150, as shown inFIG. 6B. Here, an upper surface of the insulation layer150of the exposed portion and an upper surface of the second type barrier layer143may not be coplanar with each other to form a step on the surface of the exposed portion. The second type pad electrode173may be disposed on such a step and may be prevented from being peeled off due to the step on the lower surface thereof.

The passivation layer180may cover the upper surface and the side surface of the light emitting structure120. In addition, the passivation layer180may partially cover a side surface of the second pad electrode173. The passivation layer180may protect the light emitting structure120from the outside and may also have a surface with a gentler inclination than the slope of the roughness120R on the upper surface of the first conductive type semiconductor layer121. With this structure, the light emitting diode can improve light extraction efficiency on the upper surface of the light emitting structure120. The passivation layer180may include a light transmitting insulating material, for example, SiO2.

The light emitting diode according to the exemplary embodiments includes the light emitting structure120having a non-polar or semi-polar growth plane to improve luminous efficacy and further includes the second type contact layer including the ohmic contact layer and the reflective layer to reduce contact resistance between the second type electrode and the second conductive type semiconductor layer having a non-polar or semi-polar growth plane.

FIG. 7,FIG. 8B,FIG. 9,FIG. 10,FIG. 11,FIG. 12,FIG. 13, andFIG. 14are sectional views illustrating a method of manufacturing a light emitting diode according to another exemplary embodiment of the present disclosure.FIG. 8Ais a plan view of the light emitting diode shown inFIG. 8B. Specifically,FIG. 8Bis a cross-sectional view taken along line X-X ofFIG. 8A. In descriptions of this exemplary embodiment, the same components as those of the light emitting diode described with reference toFIGS. 1, 2A, 2B, 3A, 3B, 3C, 3D, 3E, 3F, 4A, 4B, 4C, 5A, 5B, 6A, and 6Bwill be denoted by the same reference numeral and repeated descriptions thereof will be omitted.

First, referring toFIG. 7, a light emitting structure120including a first conductive type semiconductor layer121, an active layer123, and a second conductive type semiconductor layer125is formed on a growth substrate110having a non-polar or semi-polar growth plane.

The growth substrate110may be selected from any substrates having a non-polar or semi-polar growth plane and allowing the light emitting structure120to be grown thereon, and may be, for example, a sapphire substrate, a silicon carbide substrate, a silicon substrate, a gallium nitride substrate, or an aluminum nitride substrate. For example, the growth substrate110may be a nitride substrate having the m-plane, the a-plane, or a semi-polar plane as the growth plane. Here, the growth plane may be tilted at an offset angle from a specific crystal plane.

The first conductive type semiconductor layer121, the active layer123, and the second conductive type semiconductor layer125may include a Group III-V compound semiconductor, for example, a nitride semiconductor such as (Al, Ga, In)N. The first conductive type semiconductor layer121may include an n-type semiconductor layer doped with n-type dopants (for example, Si) and the second conductive type semiconductor layer125may include a p-type semiconductor layer doped with p-type dopants (for example, Mg), or vice versa. The active layer123may include a multi-quantum well (MQW) structure.

The first conductive type semiconductor layer121, the active layer123, and the second conductive type semiconductor layer125may be grown on the growth substrate110by a technique such as metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or hydride vapor phase epitaxy (HVPE). In particular, as the light emitting structure120is grown on the growth substrate110having a non-polar or semi-polar growth plane, the light emitting structure120is grown in a normal direction to the non-polar or semi-polar growth plane. Therefore, in the grown light emitting structure120, spontaneous polarization is not formed in a direction in which electrons and holes recombine, thereby improving internal quantum efficiency.

Next, referring toFIGS. 8A, 8B, and 9, at least one groove120hpartially exposing the first conductive type semiconductor layer121is formed by partially removing the light emitting structure120, while forming the second type electrode140on the second conductive type semiconductor layer125. In addition, an insulation layer150covering the second type electrode140may be further formed on the light emitting structure120. Although the second type electrode140is illustrated as being formed after formation of the at least one groove120hin this exemplary embodiment, it should be understood that the order of forming the at least one groove120hand the second type electrode140is not particularly limited.

First, referring toFIGS. 8A and 8B, the light emitting structure120may be patterned through photolithography and etching. By this process, the at least one groove120hcan be formed to have an inclined side surface by reflow of a photoresist in the photolithography and etching process. That is, as shown inFIGS. 8A and 8B, the side surface of the groove120hmay have a slope inclined at a predetermined angle with respect to a virtual line V perpendicular to the lower surface of the light emitting structure120. With the structure wherein the side surface of the groove120his inclined, step coverage of the insulation layer150and the first type electrode130formed in the subsequent processes described below can be improved.

As shown inFIG. 8A, the grooves120hmay be formed in plural and may be arranged at constant intervals. However, it should be understood that other implementations are also possible.

Referring toFIG. 9, a second type electrode140is formed on the second conductive type semiconductor layer125, and an insulation layer150having an opening150hpartially exposing the first conductive type semiconductor layer121may be formed to cover the second type electrode140and an upper surface of the light emitting structure120.

Forming the second type electrode140may include forming a second type contact layer141and forming a second type barrier layer143covering the second type contact layer141. On the other hand, the second type electrode140may be formed such that only the second type barrier layer143can be located in a region in which a second type pad electrode173will be formed by the subsequent process. That is, only the second type barrier layer143may be formed in a region, to which the second type electrode140will be exposed by partially etching the light emitting structure120in the subsequent process, such that the second type contact layer141is not exposed through the region.

Forming the second type contact layer141may include forming an ohmic contact layer contacting the second conductive type semiconductor layer125, and forming a reflective layer covering the ohmic contact layer. The structures of the ohmic contact layer and the reflective layer are substantially similar to those described with reference toFIGS. 3A, 3B, 3C, 3D, 3E, and 3F.

As described with reference toFIGS. 3A, 3B, 3C, 3D, 3E, and 3F, the ohmic contact layer may be formed by forming at least one material selected from the group consisting of Ni, Pt, Mg, Ni/Au, and a conductive oxide on the second conductive type semiconductor layer125through deposition or the like. Here, the ohmic contact layer may be formed in a film shape or in a pattern of plural islands on the second conductive type semiconductor layer125. For example, the ohmic contact layer may be formed in a film shape by forming at least one material selected from the group consisting of Ni, Pt, Mg, Ni/Au, and the conductive oxide on the second conductive type semiconductor layer125through e-beam evaporation, as shown inFIGS. 3Eand F, and may also be formed in a pattern of multiple islands regularly arranged thereon by patterning the film-shaped ohmic contact layer, as shown inFIGS. 3A and 3B. On the other hand, when the ohmic contact layer is irregularly formed on the second conductive type semiconductor layer125through adjustment of process conditions for deposition, the ohmic contact layer may have a shape, as shown inFIGS. 3C and 3D. However, it should be understood that other implementations are also possible. The reflective layer may be formed to cover the ohmic contact layer through deposition or plating of Ag and/or Al.

Further, forming the second type electrode140may further include heat treating the second type contact layer141after forming the second type contact layer141on the second conductive type semiconductor layer125. The heat treatment may be performed at a relatively low temperature (for example, at about 500° C. or less) and can prevent deterioration in reflectance of the second type contact layer141. Furthermore, in the method of manufacturing a light emitting diode according to this exemplary embodiment, since the second type contact layer141includes the ohmic contact layer and thus contact resistance between the second type contact layer141and the second conductive type semiconductor layer125can be sufficiently low, it is possible to omit the heat treatment process.

The second type barrier layer143may be formed to cover at least part of the second type contact layer141by depositing and/or plating a material selected from the group consisting of Au, Ni, Ti, W, Pt, Cu, Pd, Ta, Cr, and some combination thereof on the second type contact layer141. The second type barrier layer143may have a shape, as shown inFIGS. 4A, 4B, and 4C. In particular, when the second type barrier layer143is formed as shown inFIG. 4C, the second type barrier layer143may be formed on the second type contact layer141after a portion of the insulation layer150is formed. That is, when the second type barrier layer143is formed as shown inFIG. 4C, formation of the second type electrode140may be achieved by first forming the insulation layer150that partially exposes the second type contact layer141, forming the second type barrier layer143that partially covers the insulation layer150while contacting the exposed second type contact layer141, and additionally forming the insulation layer150so as to cover the second type barrier layer143.

The insulation layer150may be formed to cover the light emitting structure120and the second type electrode140through a deposition process such as e-beam evaporation, thermal deposition, or sputtering using a material comprising SiO2or SiNx. Furthermore, at least one opening150hmay be formed in the insulation layer150at a location corresponding to the at least one groove120hso as to expose the first conductive type semiconductor layer121by patterning the insulation layer150. Alternatively, the insulation layer150including the opening150hmay be formed by deposition and lift-off. On the other hand, dielectric layers having different indices of refraction may be repeatedly stacked one above another to form the insulation layer150including a distributed Bragg reflector.

Next, referring toFIG. 10andFIG. 11, a first type electrode130is formed to be electrically connected to the first conductive type semiconductor layer121through the opening150hwhile partially covering the insulation layer150. Forming the first type electrode130may include forming a first type contact layer131and a first type barrier layer133.

First, referring toFIG. 10, the first type contact layer131may be formed to contact the first conductive type semiconductor layer121by filling the opening150h. The first type contact layer131may be formed by forming at least one stack structure selected from the group consisting of Ti/Al, Ni/Al, Cr/Al, and Pt/Al through deposition and/or plating, and forming the first type contact layer131may further include depositing or plating a material comprising Ni, W, Pt, Cu, Ti, Pd, Ta, Au, and the like. The first type contact layer131and the first type barrier layer133may be continuously formed.

The first type contact layer131may be formed to cover the entire upper surface of the insulation layer150, as shown inFIG. 10. Alternatively, the first type contact layer131may be partially formed around the opening150hwhile filling the opening150h. In this case, the first type contact layer131may be formed as shown inFIG. 5Bto be located at a desired location through patterning or lift-off. In this case, since the first type contact layer131is formed at a particular location, the first type contact layer131and the first type barrier layer133may be intermittently formed.

Then, referring toFIG. 11, the first type barrier layer133may be formed to cover the first type contact layer131. The first type barrier layer133may be formed through deposition and/or plating a material comprising Ni, W, Pt, Cu, Ti, Pd, Ta, Au or the like in a single layer or multiple layers.

Referring toFIG. 12, the support substrate171is formed on the light emitting structure120and a bonding layer160may be further formed to bond the support substrate171and the first type electrode130.

The bonding layer160may be interposed between the support substrate171and the first type electrode130to bond the support substrate171and the first type electrode130. The bonding layer160may be formed on the first type electrode130before formation of the support substrate171and may be formed of any material capable of electrically connecting the support substrate171to the first type electrode130while bonding the same. For example, the bonding layer160may be formed by eutectic bonding, which may be achieved by depositing AuSn or the like on the first type electrode130, heating the material to an AuSn eutectic temperature (about 280° C.) or more (for example, about 350° C.), and cooling AuSn.

Next, referring toFIG. 13, the growth substrate110is separated from the light emitting structure120. In addition, the method of manufacturing a light emitting diode according to this exemplary embodiment may further include forming roughness120R on the first conductive type semiconductor layer121by increasing surface roughness of the first conductive type semiconductor layer121exposed by separation of the growth substrate110.

The growth substrate110may be removed therefrom by various methods, for example, laser lift-off, chemical lift-off, or stress lift-off. According to the method of removing the growth substrate110, additional layers may be interposed between the light emitting structure120and the growth substrate110. For example, when the growth substrate110is a nitride substrate, the material of which is the same as the material of the light emitting structure120, a sacrificial layer (not shown) may be further interposed between the growth substrate110and the light emitting structure120. In this example, the growth substrate110may be removed from the light emitting structure120by removing a portion of the sacrificial layer or by applying stress to the sacrificial layer. However, it should be understood that other implementations are also possible. Furthermore, after removing the growth substrate110from the light emitting structure120, the method may further include dicing the first conductive type semiconductor layer121to a constant thickness.

Forming the roughness120R by increasing surface roughness of the first conductive type semiconductor layer121exposed by separation of the growth substrate110may include wet etching, dry etching, or electrochemical etching. Particularly, in this exemplary embodiment, since the exposed surface of the first conductive type semiconductor layer121is a non-polar or semi-polar plane, the roughness120R may be formed by dry etching.

In the manufacturing method according to this exemplary embodiment, since the first conductive type semiconductor layer121can have a low defect density and the surface of the first conductive type semiconductor layer121exposed by separation of the growth substrate110has substantially no polarity, it is difficult to form the roughness120R only through wet etching. Thus, the roughness120R may be effectively formed on the surface of the first conductive type semiconductor layer121by dry etching or a combination of dry etching and wet etching.

Next, referring toFIG. 14, the second type barrier layer143may be partially exposed by removing a portion of the light emitting structure120to form a region120b. Then, a second type pad electrode173is formed on the region120b, followed by forming a passivation layer180, thereby providing a light emitting diode, as shown inFIGS. 2A and 2B.

The second type pad electrode173may be formed by deposition and lift-off such that a lower surface of the second type pad electrode173contacts at least part of the second type barrier layer143. The passivation layer180may be formed to cover the light emitting structure120through deposition using a material comprising SiO2or SiNx.

This exemplary embodiment provides a method of manufacturing a light emitting diode having good electrical and optical characteristics.

FIG. 15AandFIG. 15Bare plan views of a light emitting diode according to another exemplary embodiment of the present disclosure.FIG. 16is a sectional view taken along line Y-Y′ ofFIG. 15A.FIG. 15Ais a plan view of the light emitting diode according to this exemplary embodiment.FIG. 15Bis a plan view illustrating locations of grooves120hand first and second openings153a,153b.

The light emitting diode according to this exemplary embodiment is different from the light emitting diode according to the above exemplary embodiments excluding the structures of the light emitting structure120and the pad electrodes211,213. The following description will mainly focus on different features of the light emitting diode according to this exemplary embodiment and detailed descriptions of the same features will be omitted.

Referring toFIGS. 15A, 15B, and 16, the light emitting diode according to this exemplary embodiment includes a light emitting structure120, a first type electrode130, a second type electrode140, and insulation layers151,153. In addition, the light emitting diode may further include a growth substrate (not shown), a wavelength converter220, and first and second electrode pads211,213.

The light emitting structure120includes a first conductive type semiconductor layer121, an active layer123, and a second conductive type semiconductor layer125. The light emitting structure120may include at least one groove120hformed through the second conductive type semiconductor layer125and the active layer123while partially exposing the first conductive type semiconductor layer121.

The at least one groove120hmay be formed by partially removing the second conductive type semiconductor layer125and the active layer123and may be formed in plural, as shown in the drawings. Further, the second conductive type semiconductor layer125and the active layer123may be exposed to a side surface of the groove120h, and the side surface of the groove120hmay be an inclined side surface. When the at least one groove120his composed of a plurality of grooves, the shape of the grooves120hmay be modified in various ways. Since the first type electrode130is electrically connected to the first conductive type semiconductor layer121through the grooves120h, the arrangement of the grooves120hmay be modified in various ways in consideration of current dispersion and density of electric current upon driving of the light emitting diode. For example, the grooves120hmay be arranged in the form of plural dots, plural stripes, or combinations thereof. In this exemplary embodiment, the plural grooves120hmay be formed over the surface of the light emitting structure120.

In some exemplary embodiments, the second electrode pad213may have a lower region free from the groove120h. That is, as shown inFIG. 15B, the groove120hmay not be formed around the second opening153bof the second insulation layer153for electrical connection between the second electrode pad213and the second type electrode140. When the groove120his formed around a contact region between the second electrode pad213and the second type electrode140, current crowding can occur in the first conductive type semiconductor layer121near the grooves120haround the contact region, thereby causing deterioration in current spreading efficiency. Thus, in this exemplary embodiment, the groove120his not formed around the second opening153bof the second insulation layer153, particularly, under the second opening153b, thereby improving current spreading efficiency.

The grooves120hare substantially regularly arranged throughout the light emitting structure120. However, it should be understood that other implementations are also possible and the arrangement and number of grooves120hmay be modified in various ways. In addition, the exposed shape of the first conductive type semiconductor layer121is not limited to the shape of the grooves120h. For example, the first conductive type semiconductor layer121may be exposed in a line shape or a combination of hole and line shapes.

On the other hand, the light emitting structure120may be formed on a growth substrate having a non-polar or semi-polar growth plane. Thus, the light emitting structure120including the first conductive type semiconductor layer121, the active layer123, and the second conductive type semiconductor layer125may have a non-polar or semi-polar growth plane. The non-polar growth plane may include the m-plane or the a-plane.

The second type electrode140is disposed on the second conductive type semiconductor layer125to form ohmic contact with the second conductive type semiconductor layer125. The second type electrode140may be disposed to cover an upper surface of the second conductive type semiconductor layer125, or may be formed to cover substantially the entire upper surface of the second conductive type semiconductor layer125. The second type electrode140may be formed as a monolithic layer throughout the light emitting structure120. In this structure, the second type electrode140may include opening regions located corresponding to the plurality of grooves120h. With this structure, the light emitting diode allows electric current to be supplied to the entirety of the light emitting structure120, thereby improving current spreading efficiency.

The second type electrode140forming ohmic contact with the second conductive type semiconductor layer125having a non-polar or semi-polar growth plane may have the same structure as described in the above exemplary embodiments. Specifically, the second type electrode140may include a second type contact layer141and a second type barrier layer143, and the structure of the second type electrode140described with reference toFIGS. 3A, 3B, 3C, 3D, 3E, and 3Fmay also be applied to this exemplary embodiment. Accordingly, the second type contact layer141may include an ohmic contact layer1411and a reflective layer1413covering the ohmic contact layer1411. Further, as an example, the ohmic contact layer1411may include at least one material selected from the group consisting of Ni, Pt, Mg, Ni/Au, and a conductive oxide. Here, the conductive oxide may include ITO, IZO, IZTO, IAZO, IGZO, IGTO, AZO, IrOx, RuOx, RuOx/ITO, MgO, ZnO, and the like. In addition, the ohmic contact layer1411may be formed in a pattern of regularly arranged islands, a pattern of irregularly arranged islands, or a sheet (film) shape, in which the ohmic contact layer1411of each island shape may have a semi-spherical shape.

The insulation layers151,153may partially cover the light emitting structure120and the second type electrode140. The insulation layers151,153can insulate the first type electrode130and the second type electrode140from each other. Further, the insulation layers151,153may include a first insulation layer151and a second insulation layer153.

The first insulation layer151may partially cover an upper surface of the light emitting structure120and the second type electrode140. The first insulation layer151may cover side surfaces of the plurality of grooves120hand may include openings partially exposing the first conductive type semiconductor layer121located on the lower surface of the grooves120h. Thus, the openings may be disposed corresponding to arrangement of the plural grooves120h. In addition, the first insulation layer151may include an opening exposing a portion of the second type electrode140. Further, the first insulation layer151may further cover at least part of the side surface of the light emitting structure120.

The first insulation layer151may be formed of an insulating material, for example, SiO2or SiNx. Further, the upper insulation layer153may be composed of multiple layers and may include a distributed Bragg reflector in which materials having different indices of refraction are alternately stacked one above another.

The distributed Bragg reflector may be formed by repeatedly stacking dielectric layers having different indices of refraction and may have a structure of, for example, TiO2/SiO2layers alternately stacked one above another. Each layer of the distributed Bragg reflector may have an optical thickness of ¼ of a specific wavelength and the distributed Bragg reflector may be composed of 4 to 20 pairs of layers. The distributed Bragg reflector may be formed at a lower side thereof with an underlying layer capable of improving film quality of the distributed Bragg reflector. For example, the first insulation layer151may include an underlying layer having a thickness of about 0.2 μm to about 1.0 μm and formed of SiO2and a distributed Bragg reflector formed on the underlying layer and having a structure in which TiO2/SiO2layers are repeatedly stacked one above another in a predetermined number of cycles. However, it should be understood that other implementations are also possible and the distributed Bragg reflector may include dielectrics such as ZrO2, HfO2, and the like.

The distributed Bragg reflector may have a high visible light reflectance. The distributed Bragg reflector may be designed to have a reflectance of 90% or more for light having an incident angle of 0 to 60° and a wavelength of 400 nm to 700 nm. Within this range of reflectance, the distributed Bragg reflector may be provided by controlling the type, thickness, stacking period, and the like of a plurality of dielectric layers forming the distributed Bragg reflector. Accordingly, it is possible to form a distributed Bragg reflector having high reflectance with respect to light having a relatively long wavelength (for example, 550 nm to 700 nm) and light having a relatively short wavelength (for example, 400 nm to 550 nm).

The distributed Bragg reflector may include a multilayer structure so as to have high reflectance with respect to light in a broad wavelength band. That is, the distributed Bragg reflector may include a first stack structure in which dielectric layers having a first thickness are stacked and a second stack structure in which dielectric layers having a second thickness are stacked. For example, the distributed Bragg reflector may include a first stack structure in which dielectric layers having a thickness of less than ¼ of an optical thickness with respect to light at the center wavelength of visible light (about 550 nm) are stacked, and a second stack structure in which dielectric layers having a thickness of greater than ¼ of the optical thickness with respect to light at the center wavelength of visible light (about 550 nm) are stacked. The distributed Bragg reflector may further include a third stack structure in which a dielectric layer having a thickness of greater than ¼ of an optical thickness with respect to light at the center wavelength of visible light (about 550 nm) and a dielectric layer having a thickness of less than ¼ of an optical thickness with respect to light at the center wavelength of visible light (about 550 nm) are repeatedly stacked one above another.

With the distributed Bragg reflector of the first insulation layer151covering substantially the entirety of the upper surface of the light emitting structure120, the light emitting diode can have improved luminous efficacy. Particularly, light escaping from the side surfaces of the grooves120hnot covered by the second type barrier layer143of the second type electrode140can be reflected by the distributed Bragg reflector of the first insulation layer151, whereby the light emitting diode can have further improved luminous efficacy.

The first type electrode130may partially cover the light emitting structure120and may be disposed on the first insulation layer151. The first type electrode130may form ohmic contact with the first conductive type semiconductor layer121through the grooves120hand the openings of the first insulation layer151located corresponding to the grooves120h. Alternatively, the first type electrode130may be formed to cover the side surface of the light emitting structure120. In addition, the first type electrode130may include a first type contact layer131and a first type barrier layer133.

The second insulation layer153may partially cover the first type electrode130and may have a first opening153apartially exposing the first type electrode130and a second opening153bpartially exposing the second type electrode140. Each of the first and second openings153a,153bmay be formed in plural. In addition, the openings153a,153bmay be biased to opposite side surfaces. The second insulation layer153may include an insulating material, for example, SiO2, SiNx, MgF2, and the like. In some exemplary embodiments, the second insulation layer153may include a distributed Bragg reflector. In addition, when the second insulation layer153is composed of multiple layers, the uppermost layer of the second insulation layer153may be formed of SiNx. The layer formed of SiNxhas good moisture resistance to protect the light emitting diode from moisture.

The first electrode pad211and the second electrode pad213may be disposed on the light emitting structure120and may be electrically connected to the first type electrode130and the second type electrode140, respectively. Unlike the exemplary embodiment ofFIGS. 1, 2A, 2B, 3A, 3B, 3C, 3D, 3E, 3F, 4A, 4B, 4C, 5A, 5B, 6A, 6B, 7, 8A, 8B, 9, 10,11,12,13, and14, the first and second electrode pads211,213of this exemplary embodiment may be disposed on the upper surface of the light emitting structure120. Thus, the light emitting diode according to this exemplary embodiment may be flip-bonded through the first and second electrode pads211,213.

In various exemplary embodiments, the light emitting diode may further include a growth substrate (not shown). The growth substrate may be selected from any substrates having a non-polar or semi-polar growth plane and allowing the light emitting structure120to be grown thereon, and may be, for example, a sapphire substrate, a silicon carbide substrate, a silicon substrate, a gallium nitride substrate, or an aluminum nitride substrate. For example, the growth substrate may be a nitride substrate having the m-plane, the a-plane, or a semi-polar plane as the growth plane. Here, the growth plane may be tilted at an offset angle from a specific crystal plane. In the light emitting diode according to this exemplary embodiment, since the first and second electrode pads211,213are disposed on the light emitting structure120, the light emitting diode may be provided without separating the growth substrate from the light emitting structure120. Further, the growth substrate may also act to support the light emitting structure120.

The wavelength converter220may be disposed on the lower surface of the light emitting structure120. With the wavelength converter220, the light emitting diode can realize various colors through wavelength conversion of light emitted from the light emitting structure120through the wavelength converter210. In addition, the wavelength converter210may extend to the side surface of the light emitting structure120as well as the lower surface of the light emitting structure120and may further extend to a side surface of an insulation support280. In the structure wherein the light emitting diode further includes the growth substrate (not shown), the wavelength converter220may further cover a lower surface of the growth substrate. In this structure, the growth substrate may be interposed between the wavelength converter220and the light emitting structure120.

The wavelength converter220may include a material capable of converting the wavelength of light. For example, the wavelength converter220may be provided in the form of phosphors dispersed in a carrier, in the form of a single crystal phosphor sheet, or in the form of a quantum dot-containing material. However, it should be understood that other implementations are also possible. As the light emitting diode includes the wavelength converter220, a chip scale package capable of emitting white light can be provided.

FIG. 17is an exploded perspective view of one example of a lighting apparatus to which a light emitting diode according to one exemplary embodiment of the present disclosure is applied.

Referring toFIG. 17, the lighting apparatus according to this exemplary embodiment includes a diffusive cover1010, a light emitting diode module1020, and a body1030. The body1030may receive the light emitting diode module1020and the diffusive cover1010may be disposed on the body1030to cover an upper side of the light emitting diode module1020.

The body1030may have any shape so long as the body can supply electric power to the light emitting diode module1020while receiving and supporting the light emitting diode module1020. For example, as shown in the drawing, the body1030may include a body case1031, a power supply1033, a power supply case1035, and a power source connection1037.

The power supply1033is received in the power supply case1035to be electrically connected to the light emitting diode module1020, and may include at least one IC chip. The IC chip may regulate, change or control electric power supplied to the light emitting diode module1020. The power supply case1035may receive and support the power supply1033, and the power supply case1035having the power supply1033secured therein may be disposed within the body case1031. The power source connection1037is disposed at a lower end of the power supply case1035and is coupled thereto. Accordingly, the power source connection1037is electrically connected to the power supply1033within the power supply case1035and can serve as a passage through which power can be supplied from an external power source to the power supply1033.

The light emitting diode module1020includes a substrate1023and a light emitting diode1021disposed on the substrate1023. The light emitting diode module1020may be disposed at an upper portion of the body case1031and electrically connected to the power supply1033.

As the substrate1023, any substrate capable of supporting the light emitting diode1021may be used without limitation. For example, the substrate1023may include a printed circuit board having interconnects formed thereon. The substrate1023may have a shape corresponding to a securing portion formed at the upper portion of the body case1031so as to be stably secured to the body case1031. The light emitting diode1021may include at least one of the light emitting diodes according to the exemplary embodiments described above.

The diffusive cover1010is disposed on the light emitting diode1021and may be secured to the body case1031to cover the light emitting diode1021. The diffusive cover1010may be formed of a light-transmitting material and light orientation of the lighting apparatus may be adjusted through regulation of the shape and optical transmissivity of the diffusive cover1010. Thus, the diffusive cover1010may be modified in various shapes depending on usage and applications of the lighting apparatus.

FIG. 18is a cross-sectional view of one example of a display apparatus to which a light emitting diode according to one exemplary embodiment of the present disclosure is applied.

The display according to this exemplary embodiment includes a display panel2110, a backlight unit supplying light to the display panel2110, and a panel guide (not shown) supporting a lower edge of the display panel2110.

The display panel2110is not particularly limited and may be, for example, a liquid crystal panel including a liquid crystal layer. Gate driving PCBs may be further disposed at the periphery of the display panel2110to supply driving signals to a gate line. Here, the gate driving PCBs may be formed on a thin film transistor substrate instead of being formed on separate PCBs.

The backlight unit includes a light source module, which includes at least one substrate and a plurality of light emitting diodes2160. The backlight unit may further include a bottom cover2180, a reflective sheet2170, a diffusive plate2131, and optical sheets2130.

The bottom cover2180may be open at an upper side thereof to receive a substrate (not shown), the light emitting diodes2160, the reflective sheet2170, the diffusive plate2131, and the optical sheets2130. In addition, the bottom cover2180may be coupled to the panel guide. The substrate may be disposed under the reflective sheet2170to be surrounded by the reflective sheet2170. Alternatively, when a reflective material is coated on a surface thereof, the substrate may be disposed on the reflective sheet2170. Further, a plurality of substrates may be arranged parallel to one another, without being limited thereto. However, it should be understood that the light source module may include a single substrate.

The light emitting diodes2160may include at least one of the light emitting diodes according to the exemplary embodiments described above. The light emitting diodes2160may be regularly arranged in a predetermined pattern on the substrate. In addition, a lens2210may be disposed on each of the light emitting diodes2160to improve uniformity of light emitted from the plurality of light emitting diodes2160.

The diffusive plate2131and the optical sheets2130are disposed on the light emitting diode2160. Light emitted from the light emitting diode2160may be supplied in the form of sheet light to the display panel2110through the diffusive plate2131and the optical sheets2130.

In this way, the light emitting diodes according to the exemplary embodiments may be applied to direct type displays like the display according to this exemplary embodiment.

FIG. 19is a cross-sectional view of another example of the display apparatus to which a light emitting diode according to one exemplary embodiment of the present disclosure is applied.

The display according to this exemplary embodiment includes a display panel3210on which an image is displayed, and a backlight unit disposed at a rear side of the display panel3210and emitting light thereto. Further, the display includes a frame (not shown) supporting the display panel3210and receiving the backlight unit, and covers3240,3280surrounding the display panel3210.

The display panel3210is not particularly limited and may be, for example, a liquid crystal panel including a liquid crystal layer. A gate driving PCB may be further disposed at the periphery of the display panel3210to supply driving signals to a gate line. Here, the gate driving PCB may be formed on a thin film transistor substrate instead of being formed on a separate PCB. The display panel3210is secured by the covers3240,3280disposed at upper and lower sides thereof, and the cover3280disposed at the lower side of the display panel3210may be coupled to the backlight unit.

The backlight unit supplying light to the display panel3210includes a lower cover3270partially open at an upper side thereof, a light source module disposed at one side inside the lower cover3270, and a light guide plate3250disposed parallel to the light source module and converting spot light into sheet light. In addition, the backlight unit according to this exemplary embodiment may further include optical sheets3230disposed on the light guide plate3250to spread and collect light, and a reflective sheet3260disposed at a lower side of the light guide plate3250and reflecting light traveling in a downward direction of the light guide plate3250towards the display panel3210.

The light source module includes a substrate3220and a plurality of light emitting diodes3110arranged at constant intervals on one surface of the substrate3220. As the substrate3220, any substrate capable of supporting the light emitting diodes3110and being electrically connected thereto may be used without limitation. For example, the substrate3220may include a printed circuit board. The light emitting diodes3110may include at least one of the light emitting diodes according to the exemplary embodiments described above. Light emitted from the light source module enters the light guide plate3250and is supplied to the display panel3210through the optical sheets3230. The light guide plate3250and the optical sheets3230convert spot light emitted from the light emitting diodes3110into sheet light.

In this way, the light emitting diodes according to the exemplary embodiments may be applied to edge type displays like the display according to this exemplary embodiment.

FIG. 20is a cross-sectional view of a headlight to which a light emitting diode according to one exemplary embodiment of the present disclosure is applied.

Referring toFIG. 20, the headlight according to this exemplary embodiment includes a lamp body4070, a substrate4020, a light emitting diode4010, and a cover lens4050. The headlight may further include a heat dissipation unit4030, a support rack4060, and a connection member4040.

The substrate4020is secured by the support rack4060and is disposed above the lamp body4070. As the substrate4020, any member capable of supporting the light emitting diode4010may be used without limitation. For example, the substrate4020may include a substrate having a conductive pattern, such as a printed circuit board. The light emitting diode4010is disposed on the substrate4020and may be supported and secured by the substrate4020. In addition, the light emitting diode4010may be electrically connected to an external power source through the conductive pattern of the substrate4020. Further, the light emitting diode4010may include at least one of the light emitting diodes according to the exemplary embodiments described above.

The cover lens4050is disposed on a path of light emitted from the light emitting diode4010. For example, as shown in the drawing, the cover lens4050may be spaced apart from the light emitting diode4010by the connection member4040and may be disposed in a direction of supplying light emitted from the light emitting diode4010. By the cover lens4050, an orientation angle and/or a color of light emitted by the headlight can be adjusted. On the other hand, the connection member4040is disposed to secure the cover lens4050to the substrate4020while surrounding the light emitting diode4010, and thus can act as a light guide that provides a luminous path4045. The connection member4040may be formed of a light reflective material or coated therewith. On the other hand, the heat dissipation unit4030may include heat dissipation fins4031and/or a heat dissipation fan4033to dissipate heat generated upon operation of the light emitting diode4010.

In this way, the light emitting diodes according to the exemplary embodiment may be applied to headlights, particularly, headlights for vehicles, like the headlight according to this embodiment.

Although some exemplary embodiments have been described herein, it should be understood by those skilled in the art that these embodiments are given by way of illustration only, and that various modifications, variations and alterations can be made without departing from the spirit and scope of the present disclosure.