Light-emitting semiconductor device and method of fabrication

Abstract

A low-resistance silicon baseplate ( 11 ) has formed thereon a buffer layer 12 in the form of an altering lamination of AlN sublayers ( 12 a ) and GaN sublayers ( 12 b ). On this buffer layer there are formed an n-type semiconductor region ( 13 ) of gallium nitride, an active layer ( 14 ) of gallium indium nitride, and a p-type semiconductor region ( 15 ) of gallium nitride, in that order. An anode ( 17 ) is formed on the p-type semiconductor region ( 15 ), and a cathode ( 18 ) on the baseplate ( 11 ).

1 . A light-emitting semiconductor device having a gallium nitride-based compound semiconductor, characterized by comprising: 
 a baseplate ( 11 ) made from a silicon compound or silicon containing impurities and having a low resistivity;    a buffer layer ( 12 ) formed on one major surface of said baseplate and having a first layer ( 12   a ) of Al x Ga 1−x N, where 0<x≦1, and a second layer ( 12   b ) of GaN or Al y Ga 1−y N, where y<x and 0<y<1;    a semiconductor region ( 10 ) disposed on said buffer layer and containing a plurality of gallium nitride-based compound semiconductors for emission of light;    a first electrode ( 17 ) formed on part of said semiconductor region ( 10 ); and    a second electrode ( 18 ) formed on another major surface of said baseplate.    
     
     
         2 . A light-emitting semiconductor device as claimed in  claim 1 , characterized in that said semiconductor region ( 10 ) comprises: 
 a first semiconductor region ( 13 ) of a first conductivity type formed on said buffer layer ( 12 ) and composed of a gallium nitride-based compound;    an active layer ( 14 ) formed on said first semiconductor region ( 13 ); and    a second semiconductor region ( 15 ) of a second conductivity type, opposite to said first conductivity type, formed on said active layer and composed of a gallium nitride-based compound.    
     
     
         3 . A light-emitting semiconductor device as claimed in  claim 1 , characterized in that said buffer layer ( 12 ) comprises: 
 a first set of sublayers ( 12   a ) composed of Al x Ga 1−x N; and    a second set of sublayers ( 12   b ) composed of GaN or Al y Ga 1−y N;    said first and said second set of sublayers being laminated alternately.    
     
     
         4 . A light-emitting semiconductor device as claimed in  claim 1 , characterized in that said first set of sublayers ( 12   a ) of said buffer layer ( 12 ) have each a thickness ranging from 5×10 −4  micrometers to 100×10 −4  micrometers, and that said second set of sublayers ( 12   b ) of said buffer layer ( 12 ) have each a thickness ranging from 5×10 −4  micrometers to 2000×10 −4  micrometers.  
     
     
         5 . A method of fabricating a light-emitting semiconductor device having a gallium nitride-based composed semiconductor, characterized by comprising the steps of: 
 providing a baseplate ( 11 ) of monocrystalline silicon containing impurities and having a low resistivity;    forming on one major surface of said baseplate ( 11 ) a buffer layer ( 12 ) in the form of an alternation of at least one first sublayer ( 12   a ) and at least one second sublayer ( 12   b ) by a vapor phase growth method, said first sublayer ( 12   a ) being composed of Al x Ga 1−x N, where 0<x≦1, said second sublayer ( 12   b ) being composed of GaN or Al y Ga 1−y N, where y<x and 0<y<1;    forming on said buffer layer ( 12 ) by a vapor phase growth method a semiconductor region ( 10 ) composed of a plurality of gallium nitride-based compound layers for emission of light; and    forming a first electrode ( 17 ) on part of a surface of said semiconductor region ( 10 ), and a second electrode ( 18 ) on another major surface of said substrate ( 11 ).