Avalanche photodiode

Abstract

An avalanche photodiode includes at least one crystal layer having a larger band-gap than that of an absorption layer formed by a composition or material different from that of the absorption layer formed on a junction interface between a compound semiconductor absorbing an optical signal and an Si multiplication layer, and the crystal layer may be intentionally doped with n or p type impurities to cancel electrical influences of the impurities containing oxides present on the junction interface of compound semiconductor and surface of Si.

1 . An avalanche photodiode comprising: 
 an absorption layer absorbing light to create carriers; and    a multiplication layer multiplying the created carriers, wherein    the multiplication layer is formed of Si and the absorption layer is formed of a compound semiconductor, and wherein    a semiconductor interface layer having a wider band-gap than that of the absorption layer is formed between the multiplication layer and the absorption layer.    
   
   
       2 . An avalanche photodiode according to  claim 1 , wherein the absorption layer is formed of an InGaAs mixed crystal or InGaAlAs mixed crystal or InGaAsP mixed crystal, and the semiconductor interface layer is formed of the InGaAlAs mixed crystal or InGaAsP mixed crystal.  
   
   
       3 . An avalanche photodiode according to  claim 1 , wherein the absorption layer is formed of an InGaAs mixed crystal or InGaAlAs mixed crystal or InGaAsP mixed crystal, and the semiconductor interface layer is formed of InP or GaAs.  
   
   
       4 . An avalanche photodiode according to  claim 1 , wherein the absorption layer is formed of a semiconductor containing Sb.  
   
   
       5 . An avalanche photodiode according to  claim 1 , wherein a junction between the multiplication layer and the semiconductor interface layer is formed by a fusion.  
   
   
       6 . An optical module mounting an avalanche photodiode, said avalanche photodiode comprises: 
 an absorption layer absorbing light to create carriers; and    a multiplication layer multiplying the created carriers,    wherein    the multiplication layer is formed of Si and the absorption layer is formed of a compound semiconductor, and wherein    a semiconductor interface layer having a wider band-gap than that of the absorption layer is formed between the multiplication layer and the absorption layer.    
   
   
       7 . An optical receiver mounting an avalanche photodiode, said avalanche photodiode comprises: 
 an absorption layer absorbing light to create carriers; and    a multiplication layer multiplying the created carriers,    wherein    the multiplication layer is formed of Si and the absorption layer is formed of a compound semiconductor, and wherein    a semiconductor interface layer having a wider band-gap than that of the absorption layer is formed between the multiplication layer and the absorption layer.