InGaAIN light-emitting device and manufacturing method thereof
There is provided an InGaAlN light-emitting device and a manufacturing method thereof. The light emitting device includes a conductive substrate having a main surface and a back surface, a metal bonding layer formed on the main surface of the substrate, a light reflecting layer formed on the bonding layer, a semiconductor multilayer structure including at least a p-type and an n-type InGaAlN layer disposed on the reflecting layer, the p-type InGaAlN layer directly contacting the reflecting layer, and ohmic electrodes disposed on said n-type InGaAlN layer and on the back surface of the conductive substrate, respectively.
1. An In x Ga y Al 1-x-y N (0<=x<=1, 0<=y<=1) light-emitting device, the device comprising:
a conductive substrate configured with a front surface and a back surface, wherein the conductive substrate comprises a conductive Si substrate having a crystal orientation of (100), and wherein both sides of the conductive Si substrate are deposited with an ohmic contact layer stack comprising: a Pt layer, a Au layer, and a Au—In alloy layer;
a metal bonding layer situated on the front surface of the conductive substrate;
a light-reflection layer situated on the metal bonding layer;
an In x Ga y Al 1-x-y N (0<=x<=1, 0<=y<=1) semiconductor multilayer structure situated on the light-reflection layer, wherein the In x Ga y Al 1-x-y N multilayer structure comprises at least one p-type layer and one n-type layer, and wherein the p-type layer is coupled to the light-reflection layer; and wherein the conductive substrate is electrically coupled to the p-type layer via the light-reflection layer and the metal bonding layer; and
two electrodes, wherein one electrode is situated on the In x Ga y Al 1-x-y N semiconductor multilayer structure, and the other electrode is in direct contact with the back surface of the conductive substrate.
2. The In x Ga y Al 1-x-y N (0<=x<=1, 0<=y<=1) light-emitting device of claim 1 , wherein the light-reflection layer comprises at least a platinum layer.
3. The In x Ga y Al 1-x-y N (0<=x<=1, 0<=y<=1) light-emitting device of claim 1 , wherein the ohmic electrode on the InGaAlN semiconductor multilayer structure comprises a gold-germanium-nickel alloy.
4. The light-emitting device of claim 1 , wherein the conductive substrate comprises at least one of: copper, silver, nickel-cobalt ferrous alloy, and stainless steel.
5. The In x Ga y Al 1-x-y N (0<=x<=1, 0<=y<=1) light-emitting device of claim 1 , wherein the InGaA 1 N semiconductor multilayer structure is configured such that the side of the InGaA 1 N semiconductor multilayer structure which is situated closer to the conductive substrate exhibits a Ga-face, and the side of the InGaA 1 N semiconductor multilayer structure which is situated farther from the conductive substrate exhibits an N-face.
6. A method for manufacturing a light-emitting device, the method comprising:
(a) fabricating a an In x Ga y Al 1-x-y N (0<=x<=1, 0<=y<=1) semiconductor multilayer structure which comprises at least an n-type layer and a p-type layer on a silicon growth substrate;
wherein the In x Ga y Al 1-x-y N (0<=x<=1, 0<=y<=1) semiconductor multilayer structure includes a AlN buffer layer, an n-type GaN layer, a GaN/InGaN multi-quantum-well layer, and a p-type GaN layer;
wherein the outermost layer is the p-type layer;
wherein between the AlN buffer layer, which is in contact with the growth substrate, and the n-type GaN layer is an undoped GaN layer; and
wherein the AlN buffer layer can be doped or undoped;
(b) forming first a light-reflection layer and then a metal bonding layer on the surface of the In x Ga y Al 1-x-y N semiconductor multilayer structure;
(c) bonding the main surface of a conductive substrate with the first metal bonding layer; wherein the conductive substrate comprises a conductive Si substrate having a crystal orientation of 100, and wherein both sides of the conductive Si substrate are deposited with an ohmic contact layer stack comprising: a Pt layer, a Au layer, and a Au-In alloy layer, and wherein the conductive substrate is electrically coupled to the p-type layer via the light-reflection layer and the first metal bonding layer;
(d) removing the silicon growth substrate, AlN buffer layer, and undoped GaN layer situated between the AlN buffer layer, which is in contact with the growth substrate, and the n-type GaN layer to expose the n-type layer; and
(e) forming electrodes on the n-type layer and the back surface of the conductive substrate, respectively.
7. The method of claim 6 , further comprising patterning the silicon growth substrate by forming grooves and mesas thereon prior to fabricating the In x Ga y Al 1-x-y N semiconductor multilayer structure.
8. The method of claim 6 , further comprising forming an ohmic contact layer and/or a second metal bonding layer on the main surface of the conductive substrate prior to bonding the conductive substrate with the first metal bonding layer.
9. The method of claim 6 ,
wherein the silicon growth substrate is removed using an etching solution comprising nitric acid, hydrofluoric acid, and acetic acid; and
wherein removing the AlN buffer layer and undoped GaN layer comprises using dry etching techniques such as reactive ion etching and ICP etching, or wet etching techniques using concentrated phosphoric acid or alkali.