Abstract: A method for producing an AlN single crystal substrate, the method including: i) preparing a first base substrate consisting of a first AlN single crystal; ii) growing a first AlN single crystal layer over a main face of the first base substrate, to obtain a layered body; iii) cutting the first MN single crystal layer of the layered body, to separate the layered body into a second base substrate and a first part of the first AlN single crystal layer, the second base substrate including the first base substrate and a thin film layered thereon, the thin film being a second part of the first AlN single crystal layer; iv) polishing a surface of the thin film, to obtain a third base substrate consisting of a second AlN single crystal; and v) growing a second AlN single crystal layer over the polished surface of the third base substrate.

Abstract: A method for producing an AlN single crystal substrate, the method including: i) preparing a first base substrate consisting of a first AlN single crystal; ii) growing a first AlN single crystal layer over a main face of the first base substrate, to obtain a layered body; iii) cutting the first MN single crystal layer of the layered body, to separate the layered body into a second base substrate and a first part of the first AlN single crystal layer, the second base substrate including the first base substrate and a thin film layered thereon, the thin film being a second part of the first AlN single crystal layer; iv) polishing a surface of the thin film, to obtain a third base substrate consisting of a second AlN single crystal; and v) growing a second AlN single crystal layer over the polished surface of the third base substrate.

Abstract: The method for manufacturing an aluminum-based group III nitride single crystal includes the step of supplying an aluminum halide gas and a nitrogen source gas onto a base substrate, such that a reaction of the aluminum halide gas and the nitrogen source gas is conducted on the base substrate, wherein the reaction of the aluminum halide gas and the nitrogen source gas is conducted under coexistence of a halogen-based gas such that a halogen-based gas ratio (H) represented by the following formula (1) is no less than 0.1 and less than 1.0: H=VH/(VH+VAl)??(1) (In the formula (1), VH represents a supply of the halogen-based gas; and VAl represents a supply of the aluminum halide gas); and a growth rate of the aluminum-based group III nitride single crystal is no less than 10 ?m/h.

Abstract: The method for manufacturing an aluminum-based group III nitride single crystal includes the step of supplying an aluminum halide gas and a nitrogen source gas onto a base substrate, such that a reaction of the aluminum halide gas and the nitrogen source gas is conducted on the base substrate, wherein the reaction of the aluminum halide gas and the nitrogen source gas is conducted under coexistence of a halogen-based gas such that a halogen-based gas ratio (H) represented by the following formula (1) is no less than 0.1 and less than 1.0: H=VH/I(VH+VAl)??(1) (In the formula (1), VH represents a supply of the halogen-based gas; and VAl represents a supply of the aluminum halide gas); and a growth rate of the aluminum-based group III nitride single crystal is no less than 10 ?m/h.