Abstract: Provided is a semiconductor epitaxial substrate which has low semiconductor layer mosaicity and is suitable for the production of a semiconductor device. Specifically provided is a semiconductor epitaxial substrate formed by epitaxially growing a graded buffer layer which is compositionally graded such that the lattice constant increases in stages within a range from a first lattice constant to a second lattice constant larger than the first lattice constant, and a semiconductor layer produced from a semiconductor crystal having the second lattice constant on a semiconductor substrate having the first lattice constant. The angle formed by the (mnn) plane (m and n are integers except m=n=0) of the semiconductor layer and the (mnn) plane of the semiconductor substrate is set to +0.05° or more when the direction that rotates clockwise from the [100] direction to the [011] direction is positive.

Abstract: An epitaxial growth method forming a semiconductor thin film including a heterojunction of a group III-V compound semiconductor by means of molecular beam epitaxy. The method is configured to include: a first step of irradiating a molecular beam of at least one of group III elements and a molecular beam of a first group V element to form a first compound semiconductor layer; a second step of stopping the irradiation of the molecular beam of the group III element and the molecular beam of the first group V element to halt growth until an amount of the first group V element supplied is reduced to 1/10 or less of a supply of the first group V element in the first step; and a third step of irradiating a molecular beam of at least one of the group III elements and a molecular beam of a second group V element to form a second compound semiconductor layer, which is different from the first compound semiconductor, on the first compound semiconductor layer.

Abstract: An epitaxial growth method forming a semiconductor thin film including a heterojunction of a group III-V compound semiconductor by means of molecular beam epitaxy. The method is configured to include: a first step of irradiating a molecular beam of at least one of group III elements and a molecular beam of a first group V element to form a first compound semiconductor layer; a second step of stopping the irradiation of the molecular beam of the group III element and the molecular beam of the first group V element to halt growth until an amount of the first group V element supplied is reduced to 1/10 or less of a supply of the first group V element in the first step; and a third step of irradiating a molecular beam of at least one of the group III elements and a molecular beam of a second group V element to form a second compound semiconductor layer, which is different from the first compound semiconductor, on the first compound semiconductor layer.