Patent ID: 8847203

Claim:
A Group III nitride epitaxial laminate substrate comprising: a substrate; a buffer formed on the substrate; and a main laminate formed by epitaxially growing a Group III nitride layer on the buffer, wherein the buffer includes an initial growth layer in contact with the substrate, a first superlattice laminate formed on the initial growth layer, and a second superlattice laminate formed on the first superlattice laminate, the first superlattice laminate includes five to 20 sets of first AlN layers made of an AlN material and second GaN layers made of a GaN material, the first AlN layers and the second GaN layers being alternately stacked, and each one set of the first AlN layer and the second GaN layer has a thickness of less than 44 nm, the second superlattice laminate includes a plurality of sets of first layers made of an AlN material or an AlGaN material and second layers made of an AlGaN material having a different band gap from the first layers, the first and second layers being alternately stacked, the buffer is electrically insulating and electron conduction does not occur in the buffer, and an average C concentration of the second superlattice laminate is 1×10 18 /cm 3 or more.