Epitaxial growth substrate, method of producing epitaxial growth substrate, and semiconductor element

Abstract

Provided is an epitaxial growth substrate that can impart excellent performance to an optical semiconductor element. The epitaxial growth substrate includes an off substrate having a lattice constant ag and an off angle θ and a plurality of composition inclined layers stacked such that a lattice constant difference with the off substrate increases gradually from an off substrate-side. A composition inclined layer furthest from the off substrate is taken to be a pseudo substrate layer. A degree of mismatch Xαp·g that, using a surface lattice constant ag′ calculated from the lattice constant ag and the off angle θ by formula (1): ag′=ag/cosθ and a strain-affected lattice constant bp of the pseudo substrate layer calculated from X-ray diffraction measurement results, is calculated by formula (2): Xαp·g=(bp−ag′)/ag′, is 0.5% or less.

Dependencies are inferred from the claim text.