GROUND SUBSTRATE FOR GROWING GROUP III NITRIDE SEMICONDUCTOR AND METHOD FOR GROWING GROUP III NITRIDE SEMICONDUCTOR

摘要

PROBLEM TO BE SOLVED: To provide a ground substrate with which a thick-film crystal of a group III nitride semiconductor having a good surface state and cross-sectional shape can be grown.

SOLUTION: The ground substrate 112 has a first crystal growth surface 110 and a second crystal growth surface 109 which faces the same direction as a direction to which the first crystal growth surface 110 faces. The second crystal growth surface 109 is consecutively connected to at least 50% of the peripheral edge of or the whole peripheral edge of the first crystal growth surface 110 through a downward step. The first crystal growth surface 110 has a circular shape, and the second crystal growth surface 109 has a ring shape and is concentric with the first crystal growth surface 110.

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