Nitride semiconductor

Abstract

To provide a high-quality nitride semiconductor ensuring high emission efficiency of a light-emitting element fabricated. In the present invention, when obtaining a nitride semiconductor by sequentially stacking a one conductivity type nitride semiconductor part, a quantum well active layer structure part, and a another conductivity type nitride semiconductor part opposite the one conductivity type, the crystal is grown on a base having a nonpolar principal nitride surface, the one conductivity type nitride semiconductor part is formed by sequentially stacking a first nitride semiconductor layer and a second nitride semiconductor layer, and the second nitride semiconductor layer has a thickness of 400 nm to 20 μm and has a nonpolar outermost surface. By virtue of selecting the above-described base for crystal growth, an electron and a hole, which are contributing to light emission, can be prevented from spatial separation based on the QCSE effect and efficient radiation is realized. Also, by setting the thickness of the second nitride semiconductor layer to an appropriate range, the nitride semiconductor surface can avoid having extremely severe unevenness.

1 - 28 . (canceled) 
     
     
         29 . A method of producing a nitride semiconductor, which comprises growing a crystal of a nitride semiconductor on a nitride principal surface of a base having nonpolar nitride at least on one of principal surface, wherein the method comprises:
 a temperature rise stage containing a period t A  of rising the base temperature to a predetermined temperature in an atmosphere of a main flow substantially containing no hydrogen gas;   a first growth stage of epitaxially growing a first nitride semiconductor layer in an atmosphere of a main flow substantially containing no hydrogen gas; and   a second growth stage of epitaxially growing a second nitride semiconductor layer while supplying an n-type dopant raw material onto the first nitride semiconductor layer in an atmosphere of a main flow comprising hydrogen gas.   
     
     
         30 . The method of producing a nitride semiconductor as claimed in  claim 29 , wherein the main flow in the first growth stage comprises at least nitrogen gas and ammonia gas. 
     
     
         31 . The method of producing a nitride semiconductor as claimed in  claim 29 , wherein the flow ratio of nitrogen gas in the main flow in the second growth stage is 0% to 40%. 
     
     
         32 . The method of producing a nitride semiconductor as claimed in  claim 29 , wherein the average surface roughness Ra on the outermost surface of said nitride semiconductor is from 100 to 300 nm. 
     
     
         33 . The method of producing a nitride semiconductor as claimed in  claim 29 , wherein said first nitride semiconductor layer is epitaxially grown without intentionally supplying an Si raw material and is provided by allowing no intervention of other layers between said first nitride semiconductor layer and said nitride principal surface of said base. 
     
     
         34 . The method of producing a nitride semiconductor as claimed in  claim 29 , wherein said second nitride semiconductor layer has a thickness of 400 nm to 20 μm and has a substantially nonpolar outermost surface. 
     
     
         35 . The method of producing a nitride semiconductor as claimed in  claim 29 , wherein said first nitride semiconductor layer and said second nitride semiconductor layer differ from each other in the composition. 
     
     
         36 . The method of producing a nitride semiconductor as claimed in  claim 29 , wherein the nitride on said principal surface of the base is a GaN film, an AlN film, an InN film, a BN film or a mixed crystal film thereof, which is formed by crystal growth on any of a sapphire substrate, an SiC substrate, a ZnO substrate, an Si substrate, a GaN substrate, an AlN substrate, an InN substrate, a BN substrate and a self-supporting substrate comprising a mixed crystal thereof. 
     
     
         37 . The method of producing a nitride semiconductor as claimed in  claim 29 , wherein the nitride principal surface of said base is a crystal plane within ±10° or less from the (1-100) plane (m-plane). 
     
     
         38 . The method of producing a nitride semiconductor as claimed in  claim 29 , wherein at least one of said first nitride semiconductor layer and said second nitride semiconductor layer is a Group III-V nitride semiconductor comprising GaN, AlN, InN, BN or a mixed crystal thereof. 
     
     
         39 . The method of producing a nitride semiconductor as claimed in  claim 29 , wherein the thickness L 1  of said first nitride semiconductor layer is from 0.1 to 300 nm. 
     
     
         40 . The method of producing a nitride semiconductor as claimed in  claim 29 , wherein the silicon (Si) concentration in said first nitride semiconductor layer is 1×10 21  cm −3  or less. 
     
     
         41 . The method of producing a nitride semiconductor as claimed in  claim 29 , wherein the silicon concentration in said second nitride semiconductor layer is from 1×10 17  to 6×10 19  cm −3 . 
     
     
         42 . The method of producing a nitride semiconductor as claimed in  claim 29 , wherein the area of the outermost surface of said nitride semiconductor is from 30 mm 2  to 500 cm 2 .