Zinc-oxide-based light-emitting diode

Abstract

A light-emitting zinc oxide based compound semiconductor device of a double-heterostructure. The double-heterostructure includes a light-emitting layer formed of a low-resistivity Mg 1-x-y Cd x Zn y O; 0≦x<1, 0<y≦1, and x+y=0.1 to 1 compound semiconductor doped with p-type and/or n-type impurity. A first clad layer is joined to one surface of the light-emitting layer and formed of an n-type zinc oxide compound semiconductor having a composition different from the light-emitting layer. A second clad layer is joined to another surface of the light-emitting layer and formed of a low-resistivity, p-type zinc oxide based semiconductor having a composition different from the light-emitting layer.

1 . A light-emitting zinc oxide-based compound semiconductor device having a double-heterostructure comprising: 
 a light-emitting layer having first and second major surfaces and formed of a low-resistivity Mg 1-x-y  Cd x  Zn y  O; 0≦x<1, 0<y≦1, and x+y=0.1 to 1, compound semiconductor doped with an impurity;    a first clad layer joined to said first major surface of said light-emitting layer and formed of an n-type zinc-based compound semiconductor having a composition different from that of said compound semiconductor of said light-emitting layer; and    a second clad layer joined to said second major surface of said light-emitting layer and formed of a low-resistivity p-type zinc oxide-based compound semiconductor having a composition different from that of said compound semiconductor of said light-emitting layer.    
   
   
       2 . The device according to  claim 1 , wherein said compound semiconductor of said light-emitting layer is of p-type, doped with a p-type impurity.  
   
   
       3 . The device according to  claim 2 , wherein said p-type impurity comprises a Group V element.  
   
   
       4 . The device according to  claim 1 , wherein said compound semiconductor of said light-emitting layer is of n-type, doped with at least a p-conductivity type impurity.  
   
   
       5 . The device according to  claim 1 , wherein said impurity doped in said compound semiconductor of said light-emitting layer comprises a p-type impurity including a Group V element and an n-type impurity including a Group III element.  
   
   
       6 . The device according to  claim 1 , wherein said compound semiconductor of said light emitting layer is of n-type, doped with an n-type impurity.  
   
   
       7 . The device according to  claim 6 , wherein said n-type impurity comprises a group III element.  
   
   
       8 . The device according to  claim 1 , wherein said first and second clad layers are represented by the formula Mg 1-x-y  Cd x  Zn y  O; 0≦x<1, 0<y≦1, and x+y=0.1 to 1.  
   
   
       9 . The device according to  claim 1 , wherein said light-emitting layer has a thickness of 1 to 500 nanometers.  
   
   
       10 . The device according to  claim 1 , wherein said double heterostructure has an n-type ZnO contact layer joined to said first clad layer, and a p-type ZnO contact layer joined to said second clad layer.  
   
   
       11 . A light-emitting zinc-oxide-based compound semiconductor device having a double-heterostructure comprising: 
 a light-emitting layer having first and second major surfaces and formed of a low-resistivity, p-type Mg 1-x-y  Cd x  Zn y  O; 0≦x<1, 0<y≦1, and x+y=0.1 to 1 compound semiconductor doped with a p-type impurity;    a first clad layer joined to said first major surface of said light-emitting layer and formed of an n-type zinc-oxide-based compound semiconductor having a composition different from that of said compound semiconductor of said light-emitting layer; and    a second clad layer joined to said second major surface of said light-emitting layer and formed of a low-resistivity p-type zinc oxide-based compound semiconductor having a composition different from that of said compound semiconductor of said light-emitting layer.    
   
   
       12 . The device according to  claim 11 , wherein said p-type impurity doped in said compound semiconductor of said light-emitting layer comprises at least one element selected from the group consisting of arsenic, nitrogen, phosphorus, or combinations of the foregoing.  
   
   
       13 . The device according to  claim 11 , wherein said compound semiconductor of said first and second clad layer is represented by a formula: Mg 1-x-y  Cd x  Zn y  O; 0≦x<1, 0<y≦1, and x+y=0.1 to 1.  
   
   
       14 . The device according to  claim 11 , wherein said compound semiconductor of said second clad layer is represented by a formula: Mg 1-n-m  Cd n  Zn m  O; 0≦l<1, 0<m≦1, and l+m=0.1 to 1.  
   
   
       15 . The device according to  claim 11 , wherein said light-emitting layer has a thickness of 1 to 500 nanometers.  
   
   
       16 . The device according to  claim 11 , wherein said p-type impurity doped in said compound semiconductor of said light-emitting layer comprises phosphorus, and a concentration of the phosphorus is 1×10 17  to 1×10 21  atoms per cubic centimeter.  
   
   
       17 . The device according to  claim 11 , wherein said p-type impurity doped in said compound semiconductor of said second clad layer comprises nitrogen, and a concentration of the nitrogen is 1×10 17  to 1×10 21  atoms per cubic centimeter.  
   
   
       18 . The device according to  claim 11 , wherein said second clad layer has a thickness of 1 to 500 nanometers.  
   
   
       19 . The device according to  claim 11 , wherein said double-heterostructure is provided on a substrate through a buffer layer.  
   
   
       20 . The device according to  claim 11 , wherein said double-heterostructure has an n-type ZnO contact layer joined to said first clad layer, and a p-type ZnO contact layer joined to said second clad layer.  
   
   
       21 . A light-emitting zinc oxide-based compound semiconductor device having a double-heterostructure comprising: 
 a light-emitting layer having first and second major surfaces and formed of a low-resistivity, n-type Mg 1-x-y  Cd x  Zn y  O; 0≦x<1, 0<y≦1, and x+y=0.1 to 1, compound semiconductor doped with an n-type impurity;    a first clad layer joined to said first major surface of said light-emitting layer and formed of an n-type zinc-oxide-based compound semiconductor having a composition different from that of said compound semiconductor of said light-emitting layer; and    a second clad layer joined to said second major surface of said light-emitting layer and formed so a low-resistivity, p-type zinc-oxide-based compound semiconductor having a composition different from that of said compound semiconductor of said light-emitting layer.    
   
   
       22 . The device according to  claim 21 , wherein said n-type impurity doped in said compound semiconductor of said light-emitting layer comprises gallium or aluminum.  
   
   
       23 . The device according to  claim 21 , wherein said n-type impurity doped in said compound semiconductor of said light-emitting layer comprises gallium, and a concentration of the gallium is 1×10 17  to 1×10 21  atoms per cubic centimeter.  
   
   
       24 . The device according to  claim 21 , wherein said compound semiconductor of said first clad layer is represented by a formula: Mg 1-x-y  Cd x  Zn y  O; 0≦x<1, 0<y≦1, and x+y=0.1 to 1.  
   
   
       25 . The device according to  claim 21 , wherein said compound semiconductor of said second clad layer is represented by a formula: Mg 1-n-m  Cd n  Zn m  O; 0≦l<1, 0<m≦1, and n+m=0.1 to 1.  
   
   
       26 . The device according to  claim 21 , wherein said light-emitting layer has a thickness of 1 to 500 nanometers.  
   
   
       27 . The device according to  claim 21 , wherein said compound semiconductor of said second clad layer is doped with a p-type impurity comprising phosphorus, and a concentration of the phosphorus is 1×10 17  to 1×10 21  atoms per cubic centimeter.  
   
   
       28 . The device according to  claim 21 , wherein said second clad layer has a thickness of 50 to 1,500 nanometers.  
   
   
       29 . A device according to  claim 21 , wherein said double-heterostructure is provided on a substrate through a buffer layer.  
   
   
       30 . The device according to  claim 21 , wherein said double-heterostructure has an n-type ZnO contact layer joined to said first clad layer, and a p-type ZnO con-tact layer joined to said second clad layer.  
   
   
       31 . A light-emitting zinc-oxide-based compound semiconductor device having a double-heterostructure comprising: 
 a light-emitting layer having first and second major surfaces and formed of a low-resistivity, Mg 1-x-y  Cd x  Zn y  O; 0≦x<1, 0<y≦1, and x+y=0.1 to 1, compound semiconductor doped with p-type and n-type impurities;    a first clad layer joined to said first major surface of said light-emitting layer and formed of an n-type zinc-oxide-based compound semiconductor having a composition different from that of said compound semiconductor of said light-emitting layer; and    a second clad layer joined to said second major surface and formed of a low-resistivity, p-type zinc-oxide-based compound semiconductor having a composition different from that of said compound semiconductor of said light-emitting layer.    
   
   
       32 . The device according to  claim 31 , wherein said compound semiconductor of said light-emitting layer has an electron carrier concentration of 1×10 17  to 5×10 21  atoms per cubic centimeter.  
   
   
       33 . The device according to  claim 31 , wherein said compound semiconductor of said light-emitting layer is doped with not only said p-type impurity but also an n-type impurity.  
   
   
       34 . The device according to  claim 33 , wherein said p-type impurity doped in said compound semiconductor of said light-emitting layer comprises nitrogen, and said n-type impurity comprises gallium.  
   
   
       35 . The device according to  claim 31 , wherein said p-type impurity doped in said compound semiconductor of said light-emitting layer comprises at least one element selected from the group consisting of phosphorus, nitrogen, arsenic, or combinations of the foregoing.  
   
   
       36 . The device according to  claim 31 , wherein said n-type impurity doped in said compound semiconductor of said light-emitting layer comprises at least one element selected from the group consisting of aluminum, gallium, or combinations of the foregoing.  
   
   
       37 . The device according to  claim 31 , wherein said compound semiconductor of said first clad layer is represented by a formula: Mg 1-x-y  Cd x  Zn y  O; 0≦x<1, 0<y≦1, and x+y=0.1 to 1.  
   
   
       38 . The device according to  claim 31 , wherein said compound semiconductor of said second clad layer is represented by a formula: Mg 1-n-m  Cd n  Zn m  O; 0≦l<1, 0<m≦1, and n+m=0.1 to 1.  
   
   
       39 . The device according to  claim 31 , further comprising: 
 a buffer layer provided on said substrate, upon which said double-heterostructure is situated.    
   
   
       40 . The device according to  claim 31 , wherein said double-heterostructure has an n-type ZnO contact layer joined to said first clad layer, and a p-type ZnO contact layer joined to said second clad layer.  
   
   
       41 . The device according to  claim 31 , wherein 0<x<0.5.