Monolithic semiconductor laser and method of manufacturing the same

Abstract

A monolithic semiconductor laser having plural semiconductor lasers having different emission wavelengths from each other, including: a semiconductor substrate; a first double hetero-structure formed within a first area on the semiconductor substrate and having first clad layers disposed above and below a first active layer; and a second double hetero-structure formed within a second area on the semiconductor substrate and having second clad layers disposed above and below a second active layer. The first and second active layers are made of different semiconductor materials from each other. The first clad layers above and below the first active layer are of approximately the same semiconductor materials and the second clad layers above and below the second active layer are of approximately the same semiconductor materials.

1 . A monolithic semiconductor laser having plural semiconductor lasers having different emission wavelengths from each other, comprising: 
 a semiconductor substrate;    a first double hetero-structure formed within a first area on the semiconductor substrate and having first clad layers disposed above and below a first active layer; and    a second double hetero-structure formed within a second area on the semiconductor substrate and having second clad layers disposed above and below a second active layer,    wherein the first and second active layers are made of different semiconductor materials from each other, and    the first clad layers above and below the first active layer are of approximately the same semiconductor materials and the second clad layers above and below the second active layer are of approximately the same semiconductor materials.    
     
     
         2 . The monolithic semiconductor laser of  claim 1 , wherein the first double hetero-structure is a structure in which the first active layer which is a mono-layer or multi-layer of Al x1 Ga 1-x1 As (0≦x1≦1) is located between the first clad layers which are of (Al x2 Ga 1-x2 ) y2 In 1-y2 P (0≦x2≦1, 0≦y2≦1), and 
 the second double hetero-structure is a structure in which the second active layer which is a mono-layer or multi-layer of (Al x3 Ga 1-x3 ) y3 In 1-y3 P (0≦x3≦1, 0≦y3 ≦1) is located between the second clad layers which are of (Al x2 Ga 1-x2 ) y2 In 1-y2 P (0≦x 4≦1, 0 ≦y4≦1).    
     
     
         3 . The monolithic semiconductor laser of  claim 1 , wherein the first clad layers and the second clad layers are of approximately the same semiconductor materials.  
     
     
         4 . The monolithic semiconductor laser of  claim 3 , wherein the first double hetero-structure is a structure in which the first active layer which is a mono-layer or multi-layer of Al x1 Ga 1-x1 As (0≦x1≦1) is located between the first clad layers which are of (Al x2 Ga 1-x2 ) y2 In 1-y2 P (0≦x2≦1, 0≦y2≦1), and 
 the second double hetero-structure is a structure in which the second active layer which is a mono-layer or multi-layer of (Al x3 Ga 1-x3 ) y3 In 1-y3 P (0≦x3≦1, 0≦y3≦1) is located between the second clad layers which are of (Al x2 Ga 1-x2 ) y2 In 1-y2 P (0≦x2≦1, 0≦y2≦1) which is approximately the same as the first clad layers.    
     
     
         5 . The monolithic semiconductor laser of  claim 1 , wherein there are etching stopper layers each on each one of the first active layer and the second active layer.  
     
     
         6 . The monolithic semiconductor laser of  claim 1 , wherein the semiconductor layers forming the plural semiconductor lasers have approximately the same thicknesses.  
     
     
         7 . A monolithic semiconductor laser having plural semiconductor lasers having different emission wavelengths from each other, comprising: 
 a semiconductor substrate;    a first double hetero-structure formed within a first area on the semiconductor substrate and having first clad layers disposed above and below a first active layer; and    a second double hetero-structure formed within a second area on the semiconductor substrate and having second clad layers disposed above and below a second active layer,    wherein the first and second active layers are made of different semiconductor materials from each other, and    the first clad layer above the first active layer is of approximately the same semiconductor material as that of the second clad layer above the second active layer.    
     
     
         8 . The monolithic semiconductor laser of  claim 7 , wherein in the first double hetero-structure, there is the first clad layer of (Al x2 Ga 1-x2 ) y2 In 1-y2 P (0 23  x2≦1, 0≦y2≦1) on the first active layer which is a mono-layer or multi-layer of Al x1 Ga 1-x1 As (0≦x1≦1), and 
 in the second double hetero-structure, there is the second clad layer of (Al x2 Ga 1-x2 ) y2 In 1-y2 P (0≦x2≦1, 0≦y2≦1), which is approximately the same as the first clad layers, on the second active layer which is a mono-layer or multi-layer of (Al x3 Ga 1-x3 ) y3 In 1-y3 P (0≦x3≦1, 0≦y3≦1).    
     
     
         9 . The monolithic semiconductor laser of  claim 7 , wherein there are etching stopper layers each on each one of the first active layer and the second active layer.  
     
     
         10 . The monolithic semiconductor laser of  claim 7 , wherein the semiconductor layers forming the plural semiconductor lasers have approximately the same thicknesses.  
     
     
         11 . A method of manufacturing a monolithic semiconductor laser having plural semiconductor lasers having different emission wavelengths, comprising: 
 a step of preparing a semiconductor substrate;    a step of stacking within a first area on the semiconductor substrate a first semiconductor layer including a first double hetero-structure in which an active layer is disposed between an upper and a lower clad layers;    a step of stacking within a second area on the semiconductor substrate a second semiconductor layer including a second double hetero-structure in which an active layer is disposed between an upper and a lower clad layers;    a patterning step of forming an etching-resistant pattern film on the first double hetero-structure which is formed within the first area and the second double hetero-structure which is formed within the second area; and    a stripe forming step of forming stripe structures simultaneously in the first semiconductor layer of the first double hetero-structure and the second semiconductor layer of the second double hetero-structure, using the pattern film.    
     
     
         12 . The manufacturing method of  claim 11 , wherein the patterning step comprises a step of simultaneously exposing resist layers formed on the first semiconductor layer and the second semiconductor layer using a photomask.  
     
     
         13 . The manufacturing method of  claim 11 , further comprising a step of forming etching stopper layers each in an upper portion of each one of the first double hetero-structure and the second double hetero-structure, 
 wherein the stripe forming step comprises an etching step of simultaneously etching the first semiconductor layer and the second semiconductor layer using the pattern film as an etching mask and thereby exposing the etching stopper layers.    
     
     
         14 . The manufacturing method of  claim 13 , wherein the etching step is realized by a wet etching step.  
     
     
         15 . The manufacturing method of  claim 11 , wherein the etching step is a step of executing wet etching after a dry etching step and thereby exposing the etching stopper layers.  
     
     
         16 . The manufacturing method of  claim 11 , wherein the stripe forming step comprises a step of simultaneously implanting protons into the first semiconductor layer and the second semiconductor layer using the pattern film as an ion implantation mask and thereby forming high-resistance layers.