Semiconductor laser device and manufacturing method of the same

Abstract

A semiconductor laser device includes an active layer formed on a substrate, and current blocking layers formed on the substrate so as to sandwich the active layer. Each current blocking layer has a low impurity concentration at a portion near the active layer and a high impurity concentration at a portion apart from the active layer. A manufacturing method of the semiconductor laser device is also disclosed.

What is claimed is:  
     
         1 . A semiconductor laser device comprising an active layer formed on a substrate, and current blocking layers formed on the substrate so as to sandwich said active layer, wherein each current blocking layer has a low impurity concentration at a portion near said active layer and a high impurity concentration at a portion apart from said active layer.  
     
     
         2 . A device according to  claim 1 , wherein the portion of said current blocking layer near said active layer is a region  1  to 2 μm and preferably not more than 1 μm apart from an end of said active layer.  
     
     
         3 . A device according to  claim 1 , wherein said current blocking layer has an impurity concentration of 3 to 5×10 17  cm −3  at the portion near said active layer, and an impurity concentration of 7 to 10×10 17  cm −3  at the portion apart from said active layer.  
     
     
         4 . A manufacturing method of a semiconductor laser device, comprising the steps of forming an active layer on a substrate, and selectively forming current blocking layers on the substrate by metal organic vapor phase epitaxy so as to sandwich the active layer, wherein a growth condition is determined in accordance with a metal organic vapor phase epitaxy stage of each current blocking layer such that the current blocking layer near the active layer has a low impurity concentration in an initial stage of metal organic vapor phase epitaxy for the current blocking layer, and the current blocking layer apart from the active layer has a high impurity concentration in a subsequent metal organic vapor phase epitaxy stage.  
     
     
         5 . A method according to  claim 4 , wherein the growth condition is to set a growth temperature in the initial stage of metal organic vapor phase epitaxy for the current blocking layer to be lower than a subsequent growth temperature.  
     
     
         6 . A method according to  claim 4 , wherein the growth condition is to set a growth pressure in the initial stage of metal organic vapor phase epitaxy for the current blocking layer to be higher than a subsequent growth pressure.  
     
     
         7 . A method according to  claim 4 , wherein the growth condition is to set a growth rate in the initial stage of metal organic vapor phase epitaxy for the current blocking layer to be higher than a subsequent growth rate.  
     
     
         8 . A method according to  claim 4 , wherein the growth condition is to continuously supply a source gas of Group V in the initial stage of metal organic vapor phase epitaxy for the current blocking layer and to subsequently intermittently supply the source gas of Group V.  
     
     
         9 . A method according to  claim 4 , wherein the growth condition is to increase a ratio of a source gas of Group III to a source gas of Group V in the initial stage of metal organic vapor phase epitaxy for the current blocking layer and to subsequently decrease the ratio.  
     
     
         10 . A method according to  claim 5 , wherein the growth temperature in the initial stage of metal organic vapor phase epitaxy for the current blocking layer is 570° C., and the subsequent growth temperature is 650° C.  
     
     
         11 . A method according to  claim 6 , wherein the growth pressure in the initial stage of metal organic vapor phase epitaxy for the current blocking layer is 150 Torr, and the subsequent growth pressure is 50 Torr.  
     
     
         12 . A method according to  claim 7 , wherein the growth rate in the initial stage of metal organic vapor phase epitaxy for the current blocking layer is 1.5 μm/h, and the subsequent growth rate is 0.75 μm/h.  
     
     
         13 . A method according to  claim 8 , wherein the source gas of Group V is intermittently supplied in a cycle of a 1-sec supply time and 2-sec idle (non-supply) time.  
     
     
         14 . A method according to  claim 9 , wherein the ratio of the source gas of Group III to the source gas of Group V in the initial stage of metal organic vapor phase epitaxy for the current blocking layer is 500, and the subsequent ratio is 100.  
     
     
         15 . A method according to  claim 4 , wherein the initial stage of metal organic vapor phase epitaxy for the current blocking layer is a time required for growing the current blocking layer from an end of the active layer to 1 to 2 μm and preferably not more than 1 μm.