| 主权项 |
1. A method for pretreatment of a base substrate comprising the step of:
(a) heating the base substrate at a temperature range of 1000 to 1250° C. for no less than 5 minutes under a first nixed gas atmosphere, before a layer of a second group III nitride single crystal is grown, wherein the first mixed gas consists of hydrogen gas and nitrogen gas; the base substrate comprises a layer of a first group III nitride single crystal at least on a surface of the base substrate; the first group III nitride single crystal is represented by a composition formula of:
AlAGaBInCN wherein A, B, and C satisfy A+B+C=1.0, 0.5≦A≦1.0, 0≦B≦0.5, and 0≦C≦0.5; the layer of the second group III nitride single crystal is to be grown on the layer of the first group III nitride single crystal; the layer of the second group III nitride single crystal is grown directly on the layer of the first group III nitride single crystal; a surface of the layer of the first group III nitride single crystal on which the layer of the second group III nitride single crystal is to be grown has a root mean square roughness of no more than 5 nm; and the second group III nitride single crystal is a group III nitride single crystal represented by a composition formula of:
AlXGaYInZNwherein X, Y, and Z satisfy X+Y+Z=1.0, 0.5≦X≦1.0, 0≦Y≦0.5, and 0≦Z≦0.5. |
