Method for producing group-iii nitride semiconductor crystal, group-iii nitride semiconductor substrate, and semiconductor light emitting device

Abstract

The method for producing a group III nitride semiconductor crystal comprises preparing a seed crystal having a non-polar plane followed by growing a group III nitride semiconductor from the non-polar plane in a vapor phase, wherein the growing includes growing the group III nitride semiconductor so as to extend in the +C-axis direction of the seed crystal. A group III-V nitride semiconductor crystal having high quality and a large-area non-polar plane can be obtained by the method.

1 . A method for producing a group III nitride semiconductor crystal, comprising:
 preparing a seed crystal having a non-polar plane followed by growing a group III nitride semiconductor from the non-polar plane in a vapor phase,   wherein the method includes growing the group III nitride semiconductor so as to extend in the +C-axis direction (<0001> direction) of the seed crystal.   
     
     
         2 . The method for producing a group III nitride semiconductor crystal according to  claim 1 , wherein the seed crystal is selected from the group consisting of sapphire, SiC, ZnO and a group III nitride semiconductor. 
     
     
         3 . The method for producing a group III nitride semiconductor crystal according to  claim 1 , wherein the growing group III-V compound semiconductor forms a plane nearly parallel to the non-polar plane. 
     
     
         4 . The method for producing a group III nitride semiconductor crystal according to  claim 1 , wherein the seed crystal has a flat plane part, and at least a part of the peripheral part of the flat plane part includes a straight line. 
     
     
         5 . The method for producing a group III nitride semiconductor crystal according to  claim 1 , wherein the non-polar plane is a plane having an off angle within a range of ±0.2° relative to the non-polar plane of the seed crystal as measured at an accuracy within ±0.01°. 
     
     
         6 . The method for producing a group III nitride semiconductor crystal according to  claim 1 , further comprising forming a group III nitride semiconductor substrate having a C-plane, cutting the seed crystal so that the non-polar plane of the group III nitride semiconductor substrate is exposed out, and providing the seed crystal to the growing of the group III nitride semiconductor. 
     
     
         7 . The method for producing a group III nitride semiconductor crystal according to  claim 6 , wherein the seed crystal is cut through cleavage to form the non-polar plane. 
     
     
         8 . The method for producing a group III nitride semiconductor crystal according to  claim 1 , wherein the non-polar plane is a {10-10} plane or a {11-20} plane. 
     
     
         9 . The method for producing a group III nitride semiconductor crystal according to  claim 1 , wherein the growing of the group III nitride semiconductor comprises growing the group III nitride semiconductor according to an HVPE method, an MOCVD method or a sublimation method. 
     
     
         10 . The method for producing a group III nitride semiconductor crystal according to  claim 1 , wherein the group III nitride semiconductor is Al 1-x Ga x N (0≦x≦1). 
     
     
         11 . The method for producing a group III nitride semiconductor crystal according to  claim 10 , wherein the growing of the group III nitride semiconductor is attained in an atmosphere containing at least GaCl and NH 3 , and the partial pressure of GaCl is within a range of from 3×10 1  to 3×10 4  Pa and the partial pressure of NH 3  is within a range of from 1×10 3  to 3×10 5  Pa. 
     
     
         12 . The method for producing a group III nitride semiconductor crystal according to  claim 1 , comprising separating the grown group III nitride semiconductor from the seed crystal. 
     
     
         13 . A group III nitride semiconductor substrate having a non-polar plane as the surface thereof, wherein the length of the dislocation line detected in observation from the non-polar plane side thereof according to a cathodeluminescence method in the vicinity of the surface of the non-polar plane is at most 10 μm. 
     
     
         14 . The group III nitride semiconductor substrate according to  claim 13 , wherein the area of the non-polar plane is at least 5 cm 2 . 
     
     
         15 . The group III nitride semiconductor substrate according to  claim 13 , wherein the non-polar plane is a {10-10} plane or a {11-20} plane. 
     
     
         16 . The group III nitride semiconductor substrate according to  claim 13 , wherein the radius of curvature of the crystal plane as measured through XRD is at least 15 m. 
     
     
         17 . The group III nitride semiconductor substrate according to  claim 13 , wherein the group III nitride semiconductor substrate is Al 1-x Ga x N (0≦x≦1). 
     
     
         18 . A semiconductor light-emitting device having a group III nitride semiconductor substrate of  claim 13 . 
     
     
         19 . The semiconductor light-emitting device according to  claim 18 , of which the emission wavelength is at least 380 nm.