Manufacture method for ZnO based semiconductor crystal and light emitting device using same

Abstract

A manufacture method for zinc oxide (ZnO) based semiconductor crystal includes providing a substrate having a Zn polarity plane; and reacting at least zinc (Zn) and oxygen (O) on the Zn polarity plane of said substrate to grow ZnO based semiconductor crystal on the Zn polarity plane of said substrate in a Zn rich condition. (a) An n-type ZnO buffer layer is formed on a Zn polarity plane of a substrate. (b) An n-type ZnO layer is formed on the surface of the n-type ZnO buffer layer. (c) An n-type ZnMgO layer is formed on the surface of the n-type ZnO layer. (d) A ZnO/ZnMgO quantum well layer is formed on the surface of the n-type ZnMgO layer, by alternately laminating a ZnO layer and a ZnMgO layer. @(e) A p-type ZnMgO layer is formed on the surface of the ZnO/ZnMgO quantum well layer. (f) A p-type ZnO layer is formed on the surface of the p-type ZnMgO layer. @(g) An electrode is formed on the n-type ZnO layer and p-type ZnO layer. The n-type ZnO layer is formed under a Zn rich condition at the step (b).

1 . A manufacture method for zinc oxide (ZnO) based semiconductor crystal, comprising: 
 providing a substrate having a Zn polarity plane; and    reacting at least zinc (Zn) and oxygen (O) on the Zn polarity plane of said substrate to grow ZnO based semiconductor crystal on the Zn polarity plane of said substrate in a Zn rich condition.    
   
   
       2 . The manufacture method according to  claim 1 , wherein said Zn rich condition corresponds to a flux ratio of about 0.35 or smaller, the flux ratio being defied as k O ·J O /k Zn ·J Zn , where J Zn , is a flux intensity of Zn, J O  is a flux intensity of O radical, k Zn  is a Zn sticking coefficient indicating a bonding feasibility of Zn to an O terminated plane of ZnO crystal, and k O  is an O sticking coefficient indicating a bonding feasibility of O to a Zn terminated plane of ZnO crystal.  
   
   
       3 . The manufacture method according to  claim 1 , wherein the step of reacting is performed while a temperature of a surface of said substrate is set between about 740° C. and about 900° C.  
   
   
       4 . The manufacture method according to  claim 1 , wherein the step of reacting includes doping impurities of at least one of gallium (Ga), aluminum (Al) and indium (In) to the ZnO based semiconductor crystal at a concentration between about 5.0×10 17  cm −3  and about 7.0×10 19  cm −3 .  
   
   
       5 . The manufacture method according to  claim 1 , wherein the step of reacting is performed by molecular beam epitaxy.  
   
   
       6 . The manufacture method according to  claim 1 , wherein the ZnO based semiconductor crystal is a ZnO semiconductor crystal.  
   
   
       7 . The manufacture method according to  claim 1 , wherein the ZnO based semiconductor crystal is a ZnO based compound semiconductor crystal.  
   
   
       8 . A manufacture method for a ZnO based light emitting device, comprising: 
 (a) forming an n-type ZnO buffer layer on a Zn polarity plane of a substrate;    (b) forming an n-type ZnO layer over said n-type ZnO buffer layer;    (c) forming an n-type ZnMgO layer over said n-type ZnO layer;    (d) forming a ZnO/ZnMgO quantum well layer over said n-type ZnMgO layer, said ZnO/ZnMgO quantum well layer being formed by alternately laminating a ZnO layer and a ZnMgO layer;    (e) forming a p-type ZnMgO layer over said ZnO/ZnMgO quantum well layer; and    (f) forming a p-type ZnO layer over said p-type ZnMgO layer,    wherein said n-type ZnO layer is formed in a Zn rich condition in said step (b).    
   
   
       9 . The manufacture method according to  claim 8 , wherein said Zn rich condition corresponds to a flux ratio of about 0.35 or smaller, the flux ratio being defied as k O ·J O /k Zn ·J Zn , where J Zn , is a flux intensity of Zn, J O  is a flux intensity of O radical, k Zn  is a Zn sticking coefficient indicating a bonding feasibility of Zn to an O terminated plane of ZnO crystal, and k O  is an O sticking coefficient indicating a bonding feasibility of O to a Zn terminated plane of ZnO crystal.  
   
   
       10 . The manufacture method according to  claim 8 , wherein in said step (b), said n-type ZnO layer is formed while a temperature of said substrate is set between about 740° C. and about 900° C.  
   
   
       11 . The manufacture method according to  claim 8 , wherein step (b) includes doping impurities of at least one of gallium (Ga), aluminum (Al) and indium (In) to said n-type ZnO layer at a concentration between about 5.0×10 17  cm −3  and about 7.0×10 19  cm −3 .  
   
   
       12 . The manufacture method according to  claim 8 , wherein in said step (b), said n-type ZnO layer is formed by MBE.  
   
   
       13 . The manufacture method according to  claim 8 , further comprising: 
 (g) forming an electrode connected to said n-type ZnO layer; and    (h) forming an electrode connected to said p-type ZnO layer.    
   
   
       14 . A ZnO based semiconductor substrate, comprising: 
 a substrate; and    a ZnO based semiconductor film over the substrate, the ZnO based semiconductor film being doped with impurities at a concentration ranging from about 5.0×10 17  cm −3  to about 7.0×10 19  cm −3 , the ZnO based semiconductor film having an activation ratio of the impurities of about 0.5 or higher.    
   
   
       15 . The ZnO based semiconductor substrate according to  claim 14 , wherein the ZnO based semiconductor film includes ZnO crystal.  
   
   
       16 . The ZnO based semiconductor substrate according to  claim 14 , wherein the ZnO based semiconductor film includes ZnO based compound crystal.  
   
   
       17 . The ZnO based semiconductor substrate according to  claim 14 , wherein the impurities include at least one of gallium (Ga), aluminum (Al) and indium (In).  
   
   
       18 . The ZnO based semiconductor substrate according to  claim 17 , wherein the impurities include gallium (Ga).  
   
   
       19 . A ZnO based light emitting device, comprising: 
 a plurality of n-side ZnO layers; and    at least one p-type ZnO layer electrically connected to one or more of the plurality of n-type ZnO layers,    wherein at least one of the plurality of n-side ZnO layers includes a ZnO based semiconductor film doped with impurities at a concentration ranging from about 5.0×10 17  cm −3  to about 7.0×10 19  cm −3 , the ZnO based semiconductor film having an activation ratio of the impurities of about 0.5 or higher.    
   
   
       20 . The ZnO based light emitting device according to  claim 19 , wherein said plurality of n-side ZnO layers include: 
 an n-type ZnO buffer layer on a Zn polarity plane of a substrate;    an n-type ZnO layer over said n-type ZnO buffer layer;    an n-type ZnMgO layer over said n-type ZnO layer; and    a ZnO/ZnMgO quantum well layer over said n-type ZnMgO layer, said ZnO/ZnMgO quantum well layer including alternate lamination of a ZnO layer and a ZnMgO layer,    wherein the at least one p-type ZnO layer includes:    a p-type ZnMgO layer over said ZnO/ZnMgO quantum well layer; and    a p-type ZnO layer over said p-type ZnMgO layer, and    wherein said n-type ZnO layer over said n-type ZnO buffer layer corresponds to said at least one of the plurality of n-side ZnO layers.    
   
   
       21 . The ZnO based light emitting device according to  claim 19 , wherein said impurities include gallium (Ga).