Gan based group iii-v nitride semiconductor light-emitting diode and method for fabricating the same

Abstract

A GaN based III-V nitride semiconductor light-emitting device and a method for fabricating the same are provided. In the GaN based III-V nitride semiconductor light-emitting device including first and second electrodes arranged facing opposite directions or the same direction with a high-resistant substrate therebetween and material layers for light emission or lasing, the second electrode directly contacts a region of the outmost material layer exposed through an etched region of the high-resistant substrate. A thermal conductive layer may be formed on the bottom of the high-resistant substrate to cover the exposed region of the outmost material layer.

What is claimed is: 
     
         1 . A light-emitting device comprising:
 an active layer in which light is emitted;   first and second electrodes arranged facing each other around the active layer;   a first compound semiconductor layer formed between the active layer and the first electrode;   a second compound semiconductor layer, opposite to the first compound semiconductor layer, formed between the active layer and the second electrode; and   a high-resistant substrate formed on the bottom of the first compound semiconductor layer while being partially removed to allow an electrical contact between the first compound semiconductor layer and the first electrode.   
     
     
         2 . The light-emitting device of  claim 1 , wherein a via hole exposing the bottom of the first compound semiconductor layer is formed in the high-resistant substrate, and the first electrode contacts the first compound semiconductor layer through the via hole. 
     
     
         3 . The light-emitting device of  claim 1 , wherein the high-resistant substrate covers only a portion of the bottom of the first compound semiconductor layer, and the first electrode contacts a part of or the entire first compound semiconductor layer. 
     
     
         4 . The light-emitting device of  claim 1 , wherein the high-resistant substrate is a sapphire substrate. 
     
     
         5 . The light-emitting device of  claim 1 , wherein the first and second electrodes are formed of a light-transmitting material. 
     
     
         6 . The light-emitting device of  claim 5 , further comprising a pad layer partially or fully covering the second electrode. 
     
     
         7 . The light-emitting device of  claim 1 , wherein the first electrode is formed of a light-reflecting material and the second electrode is formed of a light-transmitting material. 
     
     
         8 . The light-emitting device of  claim 7 , further comprising a pad layer partially or fully covering the second electrode. 
     
     
         9 . The light-emitting device of  claim 1 , wherein the first electrode is formed of a light-transmitting material and the second electrode is formed of a light-reflecting material. 
     
     
         10 . The light-emitting device of  claim 9 , further comprising a pad layer partially or fully covering the first electrode. 
     
     
         11 . The light-emitting device of  claim 1 , wherein the first compound semiconductor layer is an n-type or undoped GaN based III-V nitride compound semiconductor layer. 
     
     
         12 . The light-emitting device of  claim 1 , wherein the second compound semiconductor layer is a p-type GaN based III-V nitride compound semiconductor layer. 
     
     
         13 . The light-emitting device of  claim 1 , wherein the active layer is an In x Al y Ga 1-x-y N layer, where 0#x#1, 0#y#1, and x+y#1. 
     
     
         14 . The light-emitting device of  claim 1 , wherein the active layer is an In x Al y Ga 1-x-y N layer having a multi-quantum well (MQW) structure, where 0#x#1, 0#y#1, and x+y#1. 
     
     
         15 . The light-emitting device of  claim 1 , wherein the first electrode comprises an ohmic contact layer covering a region of the first compound semiconductor layer exposed through the removed region of the high-resistant substrate, and a thermal conductive layer formed on the ohmic contact layer. 
     
     
         16 . A light-emitting device comprising:
 a high-resistant substrate;   first and second electrodes arranged with the high-resistant substrate therebetween; and   a material layer formed for lasing between the high-resistant substrate and the second electrode,   wherein a region of the high-resistant substrate is removed, and the first electrode contacts the material layer through the removed region of the high-resistant substrate.   
     
     
         17 . The light-emitting device of  claim 16 , wherein the material layer for lasing comprises:
 a resonator layer;   first and second cladding layers arranged with the resonator layer therebetween;   first and second compound semiconductor layers arranged on the respective first and second cladding layers; and   a passivation layer formed between the second cladding layer and the second electrode in contact with a region of the second compound semiconductor layer in a symmetrical manner,   wherein the bottom of the first compound semiconductor layer contacts the first electrode through the removed region of the high-resistant substrate.   
     
     
         18 . The light-emitting device of  claim 17 , wherein the resonator layer comprises:
 an active layer in which lasing occurs;   a first waveguide layer formed between the active layer and the first cladding layer; and   a second waveguide layer formed between the active layer and the second cladding layer.   
     
     
         19 . The light-emitting device of  claim 17 , wherein a via hole exposing the bottom of the first compound semiconductor layer is formed in the high-resistant substrate, and the first electrode contacts the first semiconductor compound layer through the via hole. 
     
     
         20 . The light-emitting device of  claim 17 , wherein the high-resistant substrate covers only a region of the bottom of the first compound semiconductor layer, and the first electrode contacts a part of or the entire of the first compound semiconductor layer. 
     
     
         21 . The light-emitting device of  claims 16 , wherein the high-resistant substrate is a sapphire substrate. 
     
     
         22 . The light-emitting device of  claims 17 , wherein the first compound semiconductor layer is an n-type or undoped GaN based III-V nitride compound semiconductor layer. 
     
     
         23 . The light-emitting device of  claim 17 , wherein the second compound semiconductor layer is a p-type GaN based III-V nitride compound semiconductor layer. 
     
     
         24 . The light-emitting device of  claim 17 , wherein the active layer is an In x Al y Ga 1-x-y N layer, where 0#x#1, 0#y#1, and x+y#1. 
     
     
         25 . The light-emitting device of  claim 17 , wherein the active layer is an In x Al y Ga 1-x-y N layer having a multi-quantum well (MQW) structure, where 0#x#1, 0#y#1, and x+y#1. 
     
     
         26 . The light-emitting device of  claim 17 , wherein the first electrode comprises an ohmic contact layer covering a region of the first compound semiconductor layer exposed through the removed region of the high-resistant substrate, and a thermal conductive layer formed on the ohmic contact layer. 
     
     
         27 . A light-emitting device comprising:
 an active layer in which light is emitted;   first and second material layers with the active layer therebetween, the first and second material layers are for inducing laser emission in the active laser by lasing;   a first electrode formed in contact with the lowermost layer of the first material layers;   a second electrode formed in contact with the uppermost layer of the second material layers in a restricted manner; and   a heat-dissipating element displaced in contact with the lowermost layer of the first material layers for effective heat dissipation.   
     
     
         28 . The light-emitting device of  claim 27 , wherein the heat-dissipating element is a thermal conductive layer, and the thermal conductive layer contacts a region of the lowermost layer of the first material layers while a substrate is present on the remaining region of the lowermost layer of the first material layers. 
     
     
         29 . The light-emitting device of  claim 28 , wherein the thermal conductive layer contacts the region of the lower most layer of the first material layers through a via hole formed in the substrate. 
     
     
         30 . The light-emitting device of  claim 29 , wherein a dent extending into the lowermost layer of the first material layers is formed along with the via hole in the substrate. 
     
     
         31 . The light-emitting device of  claim 29 , wherein the via hole is formed in a region of the substrate aligned with the first electrode. 
     
     
         32 . The light-emitting device of  claim 29 , wherein a plurality of via holes are formed in the substrate. 
     
     
         33 . The light-emitting device of  claims 29 , wherein the via hole extends past the lowermost layer of the first material layers. 
     
     
         34 . The light-emitting device of  claim 28 , wherein a region of the lowermost layer of the first material layers is etched by a predetermined thickness so that there exists a step between the region of the lowermost layer of the first material layers on which the substrate is present and the etched region of the lowermost layer where the substrate is not present. 
     
     
         35 . The light-emitting device of  claim 30 , wherein a portion of the thermal conductive layer indirectly contacts the lowermost layer of the first material layers by the dent. 
     
     
         36 . The light-emitting device of  claim 35 , wherein a plurality of dents are formed in the substrate. 
     
     
         37 . The light-emitting device of  claim 35 , wherein a via hole extending past the lowermost material layer are additionally formed in the substrate. 
     
     
         38 . The light-emitting device of  claims 27 , wherein the thermal conductive layer comprises at least one selected from the group consisting of gold (Au), silver (Ag), copper (Cu), nickel (Ni), and indium (In). 
     
     
         39 . The light-emitting device of  claims 28 , wherein the substrate is a high-resistant substrate, a silicon carbide (SiC) substrate, or a III-V compound semiconductor substrate.