Nitride-based semiconductor device and method for fabricating the same

Abstract

A nitride-based semiconductor light-emitting device 100 includes a GaN substrate 10 , of which the principal surface is an m-plane 12 , a semiconductor multilayer structure 20 that has been formed on the m-plane 12 of the GaN-based substrate 10 , and an electrode 30 arranged on the semiconductor multilayer structure 20 . The electrode 30 includes an Mg alloy layer 32 which is formed of Mg and a metal that makes an alloy with Mg less easily than Au. The Mg alloy layer 32 is in contact with a surface of a p-type semiconductor region of the semiconductor multilayer structure 20.

1 . A nitride-based semiconductor device, comprising:
 a nitride-based semiconductor multilayer structure including a p-type GaN based semiconductor region, a surface of the p-type GaN based semiconductor region being an m-plane; and   an electrode that is arranged on the p-type GaN based semiconductor region,   wherein the p-type GaN based semiconductor region is made of an Al x In y Ga z N semiconductor (where x+y+z=1, x≧0, y≧0, and z>0), and   the electrode includes a Mg alloy layer which is in contact with the surface of the p-type GaN based semiconductor region and which is made from Mg and a metal that makes an alloy with Mg less easily than Au.   
     
     
         2 . The nitride-based semiconductor device of  claim 1 , wherein a contact resistance of the electrode arranged on the m-plane is less than 1.0×10 −02  Ωcm 2 . 
     
     
         3 . The nitride-based semiconductor device of  claim 1 , wherein
 the electrode includes the Mg alloy layer and a metal layer provided directly on the Mg alloy layer, and   the metal layer is formed of a metal that makes an alloy with Mg less easily than Au.   
     
     
         4 . The nitride-based semiconductor device of  claim 3 , wherein a thickness of the Mg alloy layer is equal to or smaller than a thickness of the metal layer. 
     
     
         5 . The nitride-based semiconductor device of  claim 1 , wherein the semiconductor multilayer structure includes an active layer which includes an Al a In b Ga c N layer (where a+b+c=1, a≧0, b≧0 and c≧0), the active layer being configured to emit light. 
     
     
         6 . The nitride-based semiconductor device of  claim 1 , wherein the Mg alloy layer has a thickness of 0.1 nm to 5 nm. 
     
     
         7 . The nitride-based semiconductor device of  claim 1 , wherein, in the Mg alloy layer, a concentration of N is lower than a concentration of Ga. 
     
     
         8 . The nitride-based semiconductor device of  claim 1 , further comprising a semiconductor substrate that supports the semiconductor multilayer structure. 
     
     
         9 . A light source, comprising:
 the nitride-based semiconductor device according to  claim 1 ; and   a wavelength converter including a phosphor that converts a wavelength of light emitted from the nitride-based semiconductor device.   
     
     
         10 . A nitride-based semiconductor device, comprising:
 a nitride-based semiconductor multilayer structure including a p-type GaN based semiconductor region, a surface of the p-type GaN based semiconductor region being an m-plane; and   an electrode that is arranged on the p-type GaN based semiconductor region,   wherein the p-type GaN based semiconductor region is made of an Al x In y Ga z N semiconductor (where x+y+z=1, x≧0, y≧0, and z>0), and   the electrode includes Mg alloy islands provided on the surface of the p-type GaN based semiconductor region, the Mg alloy islands being made from Mg and a metal that makes an alloy with Mg less easily than Au.   
     
     
         11 . The nitride-based semiconductor device of  claim 10 , wherein a contact resistance of the electrode arranged on the m-plane is less than 1.0×10 −02  Ωcm 2 . 
     
     
         12 . The nitride-based semiconductor device of  claim 10 , wherein
 the electrode includes the Mg alloy islands and a metal layer provided directly on the Mg alloy islands, and   the metal layer is formed of a metal that makes an alloy with Mg less easily than Au.