Semiconductor device and method for fabricating the same

Abstract

The semiconductor device comprises a collector layer 14 ; a base layer 16 of a carbon-doped Ga x In 1-x As y Sb 1-y layer having one surface connected to the collector layer 14; an emitter layer 18 connected the other surface of the base layer 16; a base contact layer 30 of a carbon-doped GaAsSb layer electrically connected to the base layer 16; and a base electrode 32 formed on the base contact layer 30. The semiconductor device of such structure can have a much reduced base resistance R B , whereby InP/GaInAsSb-based HBTs including InP/InGaAs-based HBTs can have higher maximum oscillation frequency f max . Because of the carbon-doped semiconductor layer the semiconductor device can have higher reliability.

1 . A semiconductor device comprising: 
 a collector layer;    a base layer of a carbon-doped Ga x In 1-x As y Sb 1-y  layer having one surface connected to the collector layer;    an emitter layer connected to the other surface of the base layer;    a base contact layer of a carbon-doped GaInAsSb layer electrically connected to the base layer; and    a base electrode formed on the base contact layer.    
   
   
       2 . A semiconductor device according to  claim 1 , wherein 
 the base contact layer is lattice-matched with the base layer.    
   
   
       3 . A semiconductor device according to  claim 1 , wherein 
 the base contact layer is formed on said one surface or said the other surface of the base layer.    
   
   
       4 . A semiconductor device according to  claim 1 , wherein 
 the base contact layer is formed on a surface of the collector layer connected to the base layer and has a side surface connected to a side surface of the base layer.    
   
   
       5 . A semiconductor device according to  claim 1 , further comprising 
 the base contact layer is formed on a surface of the emitter layer connected to the base layer and has a side surface connected to a side surface of the base layer.    
   
   
       6 . A semiconductor device according to  claim 1 , further comprising a 
 surface passivation layer for protecting the base contact layer formed on the surface of the base contact layer with the base electrode formed on.    
   
   
       7 . A semiconductor device according to  claim 1 , wherein 
 an As composition y of the Ga x In 1-x As y Sb 1-y  layer is  1 , so that the base layer is formed of a InGaAs layer.    
   
   
       8 . A semiconductor device according to  claim 1 , wherein 
 a Ga composition x of the Ga x In 1-x As y Sb 1-y  layer is  1 , so that the base layer is formed of a GaAsSb layer.    
   
   
       9 . A semiconductor device according to  claim 1 , wherein 
 a dopant concentration of the base contact layer is not less than 1×10 20  cm −3 .