Iii nitride compound semiconductor substrate and a manufacturing method thereof

PROBLEM TO BE SOLVED: To provide a group III nitride-based compound semiconductor substrate which includes a p-type region formed in a limited range in plan view, the substrate having no step between the p-type region and its periphery. SOLUTION: Prior to crystal growth of a group III nitride-based compound semiconductor on a surface of a group III nitride-based compound semiconductor lower layer 6, magnesium and aluminum are both contained near a surface of the lower layer 6 within a range corresponding to the range wherein the p-type region 12 is to be formed. Since the magnesium and aluminum are both contained near the surface of the limited range of the lower layer 6, magnesium moves to the limited range of an upper layer 16 which is crystal-grown when the upper layer 16 is crystal-grown thereupon to form the p-type region 12 and the aluminum contained in the lower layer 6 limits the movement range of the magnesium, so that a containing range 10 of the magnesium of the lower layer 6 and a containing range 12 of the magnesium of the upper layer 16 are well matched with each other. COPYRIGHT: (C)2010,JPO&INPIT