Semiconductor light emitting device and its manufacturing method

Abstract

In a semiconductor light emitting device such as a semiconductor laser using nitride III-V compound semiconductors and having a structure interposing an active layer between an n-side cladding layer and a p-side cladding layer, the p-side cladding layer is made of an undoped or n-type first layer 9 and a p-type second layer 12 that are deposited sequentially from nearer to remoter from the active layer. The first layer 9 is not thinner than 50 nm. The p-type second layer 12 includes a p-type third layer having a larger band gap inserted therein as an electron blocking layer. Thus the semiconductor light emitting device is reduced in operation voltage while keeping a thickness of the p-side cladding layer necessary for ensuring favorable optical properties.

1 . A semiconductor light emitting device made by using nitride III-V compound semiconductors, which has a structure interposing an active layer between an n-side cladding layer and a p-side cladding layer, comprising: 
 the p-side cladding layer including an undoped or n-type first layer and a p-type second layer doped with a p-type impurity which lie in this order from one side nearer the active layer, and the second layer including a third layer having a larger band gap than the second layer.    
     
     
         2 . The semiconductor light emitting device according to  claim 1  wherein an n-side optical waveguide layer is interposed between the n-side cladding layer and the active layer, and a p-side optical waveguide layer is interposed between the p-side cladding layer and the active layer.  
     
     
         3 . The semiconductor light emitting device according to  claim 1  wherein the second layer of the p-side cladding layer has a thickness in the range larger than 0 nm and not exceeding 550 nm.  
     
     
         4 . The semiconductor light emitting device according to  claim 1  wherein thickness of the second layer of the p-side cladding layer is in the range from 390 nm to 550 nm.  
     
     
         5 . The semiconductor light emitting device according to  claim 1  wherein thickness of the first layer of the p-side cladding layer is in the range larger than 0 nm and not exceeding 500 nm.  
     
     
         6 . The semiconductor light emitting device according to  claim 1  wherein thickness of the first layer of the p-side cladding layer is not thinner than 50 nm.  
     
     
         7 . The semiconductor light emitting device according to  claim 1  wherein thickness of the first layer of the p-side cladding layer is in the range from 50 nm to 400 nm.  
     
     
         8 . The semiconductor light emitting device according to  claim 1  wherein the first layer of the p-side cladding layer has a superlattice structure.  
     
     
         9 . The semiconductor light emitting device according to  claim 1  wherein the p-side cladding layer has a super lattice structure.  
     
     
         10 - 12 . (CANCELLED)  
     
     
         13 . The semiconductor light emitting device according to  claim 1  wherein distance between the active layer and the second layer of the p-side cladding layer is not less than 20 nm.  
     
     
         14 . The semiconductor light emitting device according to  claim 1  wherein distance between the active layer and the second layer of the p-side cladding layer is in the range from 100 nm to 180 nm.  
     
     
         15 . The semiconductor light emitting device according to  claim 1  wherein at least one set of combined layers different in band gap or lattice constant exists between the active layer and the second layer of the p-side cladding layer.  
     
     
         16 . The semiconductor light emitting device according to  claim 1  wherein at least one layer of superlattice structure made of layers different in atomic composition ratio exists between the active layer and the second layer of the p-type cladding layer.  
     
     
         17 . (CANCELLED)  
     
     
         18 . A semiconductor light emitting device made by using nitride III-V compound semiconductors, which has a structure interposing an active layer between an n-side cladding layer and a p-side cladding layer, comprising: 
 the p-side cladding layer including an undoped or n-type first layer and a p-type second layer doped with a p-type impurity in this order from one side nearer to the active layer, and the first layer having a thickness not thinner than 50 nm.    
     
     
         19 . The semiconductor light emitting device according to  claim 18  wherein the second layer of the p-side cladding layer has a thickness in the range larger than 0 nm and not exceeding 550 nm.  
     
     
         20 . The semiconductor light emitting device according to  claim 18  wherein thickness of the second layer of the p-side cladding layer is in the range from 390 nm to 550 nm.  
     
     
         21 . The semiconductor light emitting device according to  claim 18  wherein thickness of the first layer of the p-side cladding layer is in the range from 50 nm to 400 nm.  
     
     
         22 . The semiconductor light emitting device according to  claim 18  wherein distance between the active layer and the second layer of the p-side cladding layer is not less than 20 nm.  
     
     
         23 . The semiconductor light emitting device according to  claim 18  wherein distance between the active layer and the second layer of the p-side cladding layer is in the range from 100 nm to 180 nm.  
     
     
         24 . A semiconductor light emitting device having a structure interposing an active layer between an n-side cladding layer and a p-side cladding layer, comprising: 
 the p-side cladding layer including an undoped or n-type first layer and a p-type second layer doped with a p-type impurity in this order from one side nearer to the active layer, and the first layer having a thickness not thinner than 50 nm.    
     
     
         25 . The semiconductor light emitting device according to  claim 24  wherein the second layer of the p-side cladding layer has a thickness in the range larger than 0 nm and not exceeding 550 nm.  
     
     
         26 . The semiconductor light emitting device according to  claim 24  wherein thickness of the second layer of the p-side cladding layer is in the range from 390 nm to 550 nm.  
     
     
         27 . The semiconductor light emitting device according to  claim 24  wherein distance between the ative layer and the second layer of the p-side cladding layer is not less than 20 nm.  
     
     
         28 . The semiconductor light emitting device according to  claim 24  wherein distance between the active layer and the second layer of the p-side cladding layer is in the range from 100 nm to 180 nm.  
     
     
         29 . A semiconductor light emitting device made by using nitride III-V compound semiconductors, which has a structure interposing an active layer between an n-side cladding layer and a p-side cladding layer and includes a ridge structure, comprising: 
 the p-side cladding layer including an undoped or n-type first layer and a p-type second layer doped with a p-type impurity in this order from one side nearer to the active layer, and the second layer including a third layer having a larger band gap than the second layer; and    p-type layers in opposite sides of the ridge having a thickness in the range from 0 to 100 nm.    
     
     
         30 . The semiconductor light emitting device according to  claim 29  wherein p-type layers in opposite sides of the ridge have a thickness in the range from 0 to 50 nm.  
     
     
         31 - 52 . (CANCELLED)  
     
     
         53 . A semiconductor light emitting device composed of nitride III-V compound semiconductors and having a structure interposing an active layer between an n-side cladding layer and a p-side cladding layer, comprising: 
 distance between the active layer and one of p-type layers doped with a p-type impurity nearest to the active layer being not less than 50 nm.    
     
     
         54 . The semiconductor light emitting device according to  claim 53  wherein the distance between the active layer and the p-type layer is not less than 60 nm.  
     
     
         55 . The semiconductor light emitting device according to  claim 53  wherein the distance between the active layer and the p-type layer is not less than 100 nm.  
     
     
         56 . The semiconductor light emitting device according to  claim 53  wherein the distance between the active layer and the p-type layer is in the range from 50 to 500 nm.  
     
     
         57 . The semiconductor light emitting device according to  claim 53  wherein the distance between the active layer and the p-type layer is in the range from 100 to 200 nm.  
     
     
         58 . The semiconductor light emitting device according to  claim 53  wherein the distance between the active layer and the p-type layer is in the range from 65 to 230 nm.  
     
     
         59 . The semiconductor light emitting device according to  claim 53  wherein the distance between the active layer and the p-type layer is in the range from 70 to 125 nm.  
     
     
         60 . The semiconductor light emitting device according to  claim 53  wherein the distance between the active layer and the p-type layer is in the range from 90 to 110 nm.  
     
     
         61 . The semiconductor light emitting device according to  claim 53  wherein the p-type layer nearest to the active layer has a larger band gap than that of the p-side cladding layer.  
     
     
         62 . The semiconductor light emitting device according to  claim 53  wherein at least one layer different in composition from the active layer and the p-side cladding layer is interposed between the active layer and the p-side cladding layer.  
     
     
         63 - 64 . (CANCELLED)  
     
     
         65 . A semiconductor light emitting device having a structure interposing an active layer between an n-side cladding layer and a p-side cladding layer, comprising: 
 the n-side cladding layer including an undoped or p-type first layer and an n-type second layer doped with an n-type impurity in this order from one side nearer to the active layer, and the first layer having a thickness not smaller than 50 nm.    
     
     
         66 - 67 . (CANCELLED)