Patent ID: 8541292

Claim:
A group III nitride semiconductor epitaxial substrate comprising: a sapphire substrate for growing an epitaxial film; and an ELO layer having a composition of Al x Ga 1-x N (0<x≦1) formed on top of the substrate, without forming a group III nitride layer wherein the ELO layer is a layer formed by using a mask pattern so as to prevent formation of polycrystalline growth on the mask pattern, which mask pattern is composed of carbon and is formed directly on top of the substrate, and the mask pattern reacts under a high temperature ranging from 1250° C. to 1400° C. with H 2 serving as a carrier gas or an ammonium NH 3 contained in the raw material as a nitrogen source to be eliminated such that the carbon base mask may be present between the substrate and the ELO layer.