Light emitting device

Abstract

A light emitting device includes an active layer, having a multiple quantum well structure, sandwiched between an n-type semiconductor layer and a p-type semiconductor layer. The active layer includes first and second well layers made of a nitride compound semiconductor containing In, where the second well layer emits light having a main peak wavelength which is longer than that of the first well layer. The active layer also includes an intervening barrier layer disposed between the first and second well layers, and first and second barrier layers. The first well layer isg sandwiched between the first barrier layer and the intervening barrier layer, and the second well layer is sandwiched between the second barrier layer and the intervening barrier layer. A thickness of said first barrier layer is different than a thickness of said second barrier layer.

What is claimed is:  
     
         1 . A light emitting device, comprising: 
 an active layer, having a multiple quantum well structure, sandwiched between an n-type semiconductor layer and a p-type semiconductor layer;    said active layer including, 
 first and second well layers made of a nitride compound semiconductor containing In, said second well layer emitting light having a main peak wavelength which is longer than that of said first well layer,  
 an intervening barrier layer disposed between said first and second well layers, and  
 first and second barrier layers, said first well layer being sandwiched between said first barrier layer and said intervening barrier layer, and said second well layer being sandwiched between said second barrier layer and said intervening barrier layer,  
   wherein a thickness of said first barrier layer is different than a thickness of said second barrier layer.    
     
     
         2 . The light emitting device according to  claim 1 , wherein a thickness of said intervening barrier layer is the same as the thickness of said first barrier layer.  
     
     
         3 . The light emitting device according to  claim 1 , wherein a thickness of the intervening barrier layer is the same as the thickness of said second barrier layer.  
     
     
         4 . The light emitting device according to  claim 1 , wherein the thickness of said first barrier layer is greater than the thickness of said second barrier layer.  
     
     
         5 . The light emitting device according to  claim 1 , wherein said second well layer is disposed between said first well layer and said p-type semiconductor layer.  
     
     
         6 . The light emitting device according to  claim 1 , wherein the thickness of each of the first and second well layers is not greater than 100 angstroms.  
     
     
         7 . The light emitting device according to  claim 1 , wherein the thickness of each of said first and second barrier layers is greater than a thickness of each of said first and second well layers.  
     
     
         8 . The light emitting device according to  claim 1 , wherein said active layer further includes a plurality of said first well layers, and a plurality of said first barrier layers, and wherein at least one of said first well layers is sandwiched between said first barrier layers.  
     
     
         9 . The light emitting device according to  claim 1 , wherein said active layer further includes a plurality of said second well layers, and a plurality of said second barrier layers, and wherein at least one of said second well layers is sandwiched between said second barrier layers.  
     
     
         10 . The light emitting device according to  claim 1 , wherein a light spectrum of the light emitted by said first well layer is a half-width narrower than that emitted by said second well layer.  
     
     
         11 . The light emitting device according to  claim 1 , wherein the main peak wavelength of the light emitted by said first well layer is in the range of 450 to 500 nm, and wherein the main peak wavelength of the light emitted by said second well layer is within the range of 560 to 670 nm.  
     
     
         12 . A light emitting device comprising: 
 an active layer, having a multiple quantum well structure, sandwiched between an n-type semiconductor layer and a p-type semiconductor layer;    said active layer including, 
 at least one first well layer made of a nitride compound semiconductor containing In, and  
 at least one second well layer made of a nitride compound semiconductor containing In, said second well layer emitting light having a main peak wavelength which is longer than that of said first well layer, and  
 a plurality of barrier layers including a first barrier layer, a second barrier layer and a third barrier layer,  
 wherein said first barrier layer, said first well layer, said second barrier layer, said second well layer and said third barrier layer are laminated in order, and  
 wherein a thickness of each of said first and second barrier layers is greater than a thickness of said third barrier layer.  
   
     
     
         13 . The light emitting device according to  claim 12 , wherein said second well layer is disposed between said first well layer and said p-type semiconductor layer.  
     
     
         14 . The light emitting device according to  claim 13 , wherein the thickness of said first barrier layer is the same as the thickness of said second barrier layer.  
     
     
         15 . The light emitting device according to  claim 13 , wherein the thickness of each the first and second well layers is not greater than 100 angstroms.  
     
     
         16 . The light emitting device according to  claim 14 , wherein the thickness of each of the barrier layers is greater than a thickness of each of the first and second well layers.  
     
     
         17 . The light emitting device according to  claim 13 , wherein a light spectrum of the light emitted by said first well layer is a half-width narrower than that emitted by said second well layer.  
     
     
         18 . The light emitting device according to  claim 13 , wherein the main peak wavelength of the light emitted by said first well layer is in the range of 450 to 500 nm, and wherein the main peak wavelength of the light emitted by said second well layer is within the range of 560 to 670 nm.  
     
     
         19 . The light emitting device according to  claim 13 , wherein a growth number of said first well layer is greater than that of said second well layer.  
     
     
         20 . A light emitting device comprising: 
 an active layer, having a multiple quantum well structure, sandwiched between an n-type semiconductor layer and a p-type semiconductor layer;    said active layer including, 
 at least one first well layer made of a nitride compound semiconductor containing In, and  
 at least one second well layer made of a nitride compound semiconductor containing In, said second well layer emitting light having a main peak wavelength which is longer than that of said first well layer, and  
 a plurality of barrier layers including a first barrier layer, a second barrier layer and a third barrier layer,  
 wherein said first barrier layer, said first well layer, said second barrier layer, said second well layer and said third barrier layer are laminated in order, and  
 wherein a thickness of each of said second and third barrier layers is less than a thickness of said first barrier layer.  
   
     
     
         21 . The light emitting device according to  claim 20 , wherein said second well layer is disposed between said first well layer and said p-type semiconductor layer.  
     
     
         22 . The light emitting device according to  claim 21 , wherein the second and third barrier layers have the same thickness.  
     
     
         23 . The light emitting device according to  claim 21 , wherein a thickness of each of the first and second well layers is not greater than 100 angstroms.  
     
     
         24 . The light emitting device according to  claim 23 , wherein the thickness of each of the barrier layers is greater than a thickness of each of the first and second well layers.  
     
     
         25 . The light emitting device according to  claim 21 , wherein a light spectrum of the light emitted by said first well layer is a half-width narrower than that emitted by said second well layer.  
     
     
         26 . The light emitting device according to  claim 21 , wherein the main peak wavelength of the light emitted by said first well layer is in the range of 450 to 500 nm, and wherein the main peak wavelength of the light emitted by said second well layer is within the range of 560 to 670 nm.  
     
     
         27 . The light emitting device according to  claim 21 , wherein a growth number of said first well layer is greater than that of said second well layer.