Optical semiconductor device having active layer and carrier recombination layer different from each other

Abstract

In an optical semiconductor device including a semiconductor substrate, an active layer formed on the semiconductor substrate, a pnpn-type current blocking layer formed on a side of the active layer, and a carrier recombination layer on the semiconductor substrate on the side of the active layer, a structure of the active layer is different from a structure of the carrier recomibination layer.

1 . An optical semiconductor device comprising: 
 a semiconductor substrate;    an active layer formed on said semiconductor-substrate;    a pnpn-type current blocking layer formed on a side of said active layer; and    a carrier recombination layer on said semiconductor substrate on the side of said active layer,    a structure of said active layer being different from a structure of said carrier recombination layer.    
     
     
         2 . The device as set forth in  claim 1 , wherein said carrier recombination layer is beneath said pnpn-type current blocking layer.  
     
     
         3 . The device as set forth in  claim 1 , wherein said carrier recombination layer is in contact with said active layer.  
     
     
         4 . The device as set forth in  claim 1 , wherein said semiconductor substrate is an n-type InP substrate, 
 said device further comprising a p-type InP clad layer on said active layer and said pnpn-type current blocking layer.    
     
     
         5 . The device as set forth in  claim 4 , further comprising an n-type InP clad layer between said n-type InP substrate and said active layer.  
     
     
         6 . The device as set forth in  claim 1 , wherein a bandgap of said carrier recombination layer is larger than a bandgap of said active layer.  
     
     
         7 . The device as set forth in  claim 1 , wherein said active layer comprises a multiple quantum well layer consisting of a plurality of periods each formed by one well layer and one barrier layer, and said carrier recombination layer comprises a single layer.  
     
     
         8 . The device as set forth in  claim 7 , wherein said carrier recombination layer is made of i-type InGaAsP.  
     
     
         9 . An optical semiconductor device comprising: 
 an n-type InP substrate;    an n-type InP clad layer on said n-type InP substrate;    a multiple quantum well active layer formed on said n-type InP clad layer,    a pair of i-type carrier recombination layers, each formed on said n-type InP substrate on one side of said n-type InP clad layer; and    a pair of pnpn-type current blocking layers, each formed on one of said i-type carrier recombination layers on one side of said multiple quantum well active layer.    
     
     
         10 . The device as set forth in  claim 9 , wherein said i-type carrier recombination layers are made of i-type InGaAsP.  
     
     
         11 . The device as set forth in  claim 9 , further comprising a p-type InP clad layer on said multiple quantum well active layer and said pnpn-type current blocking layers.  
     
     
         12 . A method for manufacturing an optical semiconductor device, comprising the steps of: 
 sequentially growing an i-type carrier recombination layer and a first semiconductor layer of a first conductivity type by a metal-organic vapor epitaxy (MOVPE) process on a semiconductor substrate of a second conductivity type;    forming a first mask pattern having a striped space on said first semiconductor layer;    etching said first semiconductor layer and said i-type carrier recombination layer by using said first mask pattern;    sequentially growing a second semiconductor layer of said second conductivity type, a multiple quantum well active layer and a third semiconductor layer of said first conductivity type by an MOVPE process using said first mask pattern on said semiconductor substrate;    removing said first mask pattern after said second semiconductor layer, said multiple quantum well active layer and said third semiconductor layer are grown;    forming a second mask pattern only on said third semiconductor layer after said first mask pattern is removed;    sequentially growing a fourth semiconductor layer of said first conductivity type, a fifth semiconductor layer of said second conductivity type and a sixth semiconductor layer of said first conductivity type by an MOVPE process using said second mask pattern;    removing said second mask pattern after said fourth, fifth and sixth semiconductor layers are grown; and    sequentially growing a seventh semiconductor layer of said first conductivity type and a semiconductor cap layer of said first conductivity type by an MOVPE process after said second mask pattern is removed.    
     
     
         13 . The method as set forth in  claim 12 , wherein said semiconductor substrate and said second and fifth semiconductor layers are made of n-type InP, 
 said first, third, fourth, fifth, sixth and seventh semiconductor layers being made of p-type InP,    said i-type carrier recombination layer being made of i-type InGaAsP,    said semiconductor cap layer being made of p-type InGaAs.    
     
     
         14 . A method for manufacturing an optical semiconductor device, comprising the steps of: 
 forming a first mask pattern having a striped space on a semiconductor substrate of a second conductivity type;    sequentially growing a first semiconductor layer of said second conductivity type, a multiple quantum well active layer and a second semiconductor layer of a first conductivity type by a metal-organic vapor epitaxy (MOVPE) process using said first mask pattern on said semiconductor substrate;    removing said first mask pattern after said first semiconductor layer, said multiple quantum well active layer and said second semiconductor layer are grown;    forming a second mask pattern on said second semiconductor layer and said semiconductor substrate near said multiple quantum well active layer after said first mask pattern is removed;    growing an i-type carrier recombination layer by an MOVPE process using said second mask pattern on said semiconductor substrate;    removing said second mask pattern after said i-type carrier recombination layer is removed;    forming a third mask pattern only on said second semiconductor layer after said second mask pattern is removed;    sequentially growing a third semiconductor layer of said first conductivity type, a fourth semiconductor layer of said second conductivity type and a fifth semiconductor layer of said first conductivity type by an MOVPE process using said third mask pattern;    removing said third mask pattern after said third, fourth and fifth semiconductor layers are grown; and    sequentially growing a sixth semiconductor layer of said first conductivity type and a semiconductor cap layer of said first conductivity type by an MOVPE process after said third mask pattern is removed.    
     
     
         15 . The method as set forth in  claim 14 , wherein said semiconductor substrate and said first and fourth semiconductor layers are made of n-type InP, 
 said second, third, fifth and sixth semiconductor layers being made of p-type InP,    said i-type carrier recombination layer being made of i-type InGaAsP,    said semiconductor cap layer being made of p-type InGaAs.    
     
     
         16 . A method for manufacturing an optical semiconductor device, comprising the steps of: 
 forming a first mask pattern having a striped space on a semiconductor substrate of a second conductivity type;    sequentially growing a first semiconductor layer of said second conductivity type, a multiple quantum well active layer and a second semiconductor layer of a first conductivity type by a metal-organic vapor epitaxy (MOVPE) process using said first mask pattern on said semiconductor substrate;    removing said first mask pattern after said first semiconductor layer, said multiple quantum well active layer and said second semiconductor layer are grown;    forming a second mask pattern only on said second semiconductor layer after said first mask pattern is removed;    sequentially growing an i-type carrier recombination layer, a third semiconductor layer of said first conductivity type, a fourth semiconductor layer of said second conductivity type and a fifth semiconductor layer of said first conductivity type by an MOVPE process using said second mask pattern;    removing said second mask pattern after said i-type carrier recombination layer, said third, fourth and fifth semiconductor layers are grown; and    sequentially growing a sixth semiconductor layer of said first conductivity type and a semiconductor cap layer of said first conductivity type by an MOVPE process after said second mask pattern is removed.    
     
     
         17 . The method as set forth in  claim 16 , wherein said semiconductor substrate and said first and fourth semiconductor layers are made of n-type InP, 
 said second, third, fifth and sixth semiconductor layers being made of p-type InP,    said i-type carrier recombination layer being made of i-type InGaAsP,    said semiconductor cap layer being made of p-type InGaAs.    
     
     
         18 . A method for manufacturing an optical semiconductor device, comprising the steps of: 
 forming a first mask pattern having a striped space on a semiconductor substrate of a second conductivity type;    sequentially growing an i-type carrier recombination layer and a first semiconductor layer of a first conductivity type by a metal-organic vapor epitaxy (MOVPE) process using the first mask pattern;    removing said first mask pattern after said i-type carrier recombination layer and said first semiconductor layer are grown;    forming a second mask pattern on said first semiconductor layer after said first mask pattern is removed;    sequentially growing a second semiconductor layer of said second conductivity type, a multiple quantum well active layer and a third semiconductor layer of a first conductivity type by a MOVPE process using said second mask pattern on said semiconductor substrate;    removing said second mask pattern after said second semiconductor layer, said multiple quantum well active layer and said third semiconductor layer are grown;    forming a third mask pattern only on said third semsemiconductor layer after said second mask pattern is removed;    sequentially growing a fourth semiconductor layer of said first conductivity type, a fifth semiconductor layer of said second conductivity type and a sixth semiconductor layer of said first conductivity type by an MOVPE process using said third mask pattern;    removing said third mask pattern after said fourth, fifth and sixth semiconductor layers are grown; and    sequentially growing a seventh semiconductor layer of said first conductivity type and a semiconductor cap layer of said first conductivity type by an MOVPE process after said third mask pattern is removed.    
     
     
         19 . The method as set forth in  claim 18 , wherein said semiconductor substrate and said second and fifth semiconductor layers are made of n-type InP, 
 said first, third, fourth and sixth semiconductor layers being made of p-typo InP,    said i-type carrier recombination layer being made of i-type lnGaAsP,    said semiconductor cap layer being made of p-type InGaAs.    
     
     
         20 . A method for manufacturing an optical semiconductor device, comprising the steps of: 
 growing an i-type carrier recombination layer by a metal-organic vapor epitaxy (MOVPE) process on a semiconductor substrate of a second conductivity type;    forming a first mask pattern having a first striped space on said i-type carrier recombination layer;    etching said i-type carrier recombination layer by suing said first mask pattern;    removing said first mask pattern after said i-type carrier recombination layer is etched;    forming a second mask pattern having a second striped space smaller than said first striped space on said semiconductor substrate and said i-type carrier recombination layer after said first mask pattern is removed;    growing a first semiconductor layer of said second conductivity type, a multiple quantum well active layer and a second semiconductor layer of a first conductivity type by an MOVPE process using said second mask pattern on said semiconductor substrate;    removing said second mask pattern after said first semiconductor layer, said multiple quantum well active layer and said second semiconductor layer are grown;    forming a third mask pattern only on said second semiconductor layer after said second mask pattern is removed;    sequentially growing a third semiconductor layer of said first conductivity type, a fourth semiconductor layer of said second conductivity type and a fourth semiconductor layer of said first conductivity type by an MOVPE process using said third mask pattern;    removing said third mask pattern after said third, fourth and fifth semiconductor layers are grown; and    sequentially growing a sixth semiconductor layer of said first conductivity type and a semiconductor cap layer of said first conductivity type by an MOVPE process after said third mask pattern is removed.    
     
     
         21 . The method as set forth in claim  20 , wherein said semiconductor substrate and said first, fourth and sixth semiconductor layer are made of n-type InP, 
 said second, third, fifth and sixth semiconductor layers being made of p-type InP,    said i-type carrier recombination layer being made of i-type InGaAsP,    said semiconductor cap layer being made of p-type InGaAs.