Method for producing a group iii nitride semiconductor single crystal and method for producing a gan substrate

Abstract

The present invention provides a method for producing a Group III nitride semiconductor single crystal having excellent crystallinity, and a method for producing a GaN substrate having excellent crystallinity, the method including controlling melting back. Specifically, a mask layer is formed on a GaN substrate serving as a growth substrate. Then, a plurality of trenches which penetrate the mask layer and reach the GaN substrate are formed through photolithography. The obtained seed crystal and raw materials of a single crystal are fed to a crucible and subjected to treatment under pressurized and high temperature conditions. Portions of the GaN substrate exposed to the trenches undergo melting back with a flux. Through dissolution of the GaN substrate, the dimensions of the trenches increase, to provide large trenches. The GaN layer is grown from the surface of the mask layer as a starting point.