Light emitting semiconductor device and method for manufacturing

Abstract

The light emitting semiconductor device ( 1 ) of the present invention is made of nitrides of group III metals and comprises a layer structure comprising an n-type semiconductor layer ( 2 ), a p-type semiconductor layer ( 3 ), an active region ( 4 ) between the n-type semiconductor layer and the p-type semiconductor layer. The layer structure has a contact surface ( 5 ) defined by one of the n-type and p-type semiconductor layers and comprises further a reflective contact structure ( 6 ) attached to the contact surface. According to the present invention, the reflective contact structure ( 6 ) comprises: a first transparent conductive oxide (TCO) contact layer ( 13 ), having a poly-crystalline structure, attached to the contact surface ( 5 ) of the layer structure; a second transparent conductive oxide (TCO) contact layer ( 14 ) having an amorphous structure; and a metallic reflective layer ( 15 ) attached to the second TCO layer.

1 . A light emitting semiconductor device ( 1 ) made of nitrides of group III metals, the device comprising a layer structure comprising an n-type semiconductor layer ( 2 ), a p-type semiconductor layer ( 3 ), an active region ( 4 ) between the n-type semiconductor layer and the p-type semiconductor layer, the layer structure having a contact surface ( 5 ) defined by one of the n-type and p-type semiconductor layers, the structure further comprising a reflective contact structure ( 6 ) attached to the contact surface, characterized in that the reflective contact structure ( 6 ) comprises:
 a first transparent conductive oxide (TCO) contact layer ( 13 ), having a polycrystalline structure, attached to the contact surface ( 5 ) of the layer structure,   a second transparent conductive oxide (TCO) contact layer ( 14 ) having an amorphous structure, and   a metallic reflective layer ( 15 ) attached to the second TCO layer.   
     
     
         2 . A semiconductor device ( 1 ) according to  claim 1 , characterized in that the chemical composition of the first TCO contact layer ( 13 ) is selected to promote strong adhesion to the contact surface ( 5 ) of the layer structure, good transparency, and high electrical conductivity of the first TCO contact layer, and the chemical composition of the second TCO contact layer ( 14 ) is selected to promote strong adhesion of the metallic reflective layer ( 15 ) to the second TCO contact layer. 
     
     
         3 . A semiconductor device ( 1 ) according to  claim 1 , characterized in that the layer ( 3 ) defining the contact surface comprises p-type InGaN. 
     
     
         4 . A semiconductor device ( 1 ) according to  claim 1 , characterized in that the first TCO contact layer ( 13 ) comprises indium tin oxide. 
     
     
         5 . A semiconductor device ( 1 ) according to  claim 1 , characterized in that the first TCO contact layer ( 13 ) has a thickness of 30-500 nm, preferably of 100-150 nm. 
     
     
         6 . A semiconductor device ( 1 ) according to  claim 1 , characterized in that the second TCO contact layer ( 14 ) comprises aluminum zinc oxide, and the metallic reflective layer ( 15 ) comprises aluminum deposited on the second TCO contact layer. 
     
     
         7 . A semiconductor device ( 1 ) according to  claim 1 , characterized in that the second TCO contact layer ( 14 ) has a thickness of 0.2-20 nm, preferably of 1-3 nm. 
     
     
         8 . A method for manufacturing a light emitting semiconductor device ( 1 ) made of nitrides of group III metals, the method comprising fabricating a layer structure comprising an n-type semiconductor layer ( 2 ), a p-type semiconductor layer ( 3 ), an active region ( 4 ) between the n-type semiconductor layer and the p-type semiconductor layer, the layer structure having a contact surface ( 5 ) defined by one of the n-type and p-type semiconductor layers, the method further comprising forming a reflective contact structure ( 6 ) on the contact surface, characterized in that forming the reflective contact structure ( 6 ) comprises the steps of:
 forming a first transparent conductive oxide (TCO) contact layer ( 13 ), having a polycrystalline structure, on the contact surface ( 5 ) of the layer structure,   forming a second transparent conductive oxide (TCO) contact layer ( 14 ) having an amorphous structure, and   forming a metallic reflective layer ( 15 ) on the second TCO layer.   
     
     
         9 . A method according to  claim 8 , characterized in that the chemical composition of the first TCO contact layer ( 13 ) is selected to promote strong adhesion to the contact surface ( 5 ) of the layer structure, good transparency, and high electrical conductivity of the first TCO contact layer, and the chemical composition of the second TCO contact layer ( 14 ) is selected to promote strong adhesion of the metallic reflective layer ( 15 ) to the second TCO layer. 
     
     
         10 . A method according to  claim 8 , characterized in that the layer ( 3 ) defining the contact surface ( 5 ) comprises p-type InGaN. 
     
     
         11 . A method according to  claim 8 , characterized in that the first TCO contact layer ( 13 ) comprises indium tin oxide. 
     
     
         12 . A method according to  claim 8 , characterized in that the first TCO contact layer ( 13 ) is fabricated to have a thickness of 30-500 nm, preferably of 100-150 nm. 
     
     
         13 . A method according to  claim 8 , characterized in that the second TCO contact layer ( 14 ) comprises aluminum zinc oxide, and the step of forming the metallic reflective layer ( 15 ) comprises depositing aluminum on the second TCO contact layer. 
     
     
         14 . A method according to  claim 8 , characterized in that the second TCO contact layer ( 14 ) is fabricated to have a thickness of 0.2-20 nm, preferably of 1-3 nm.