GROUP III NITRIDE SEMICONDUCTOR DEVICE, EPITAXIAL SUBSTRATE, AND METHOD FOR MANUFACTURING GROUP III NITRIDE SEMICONDUCTOR DEVICE

摘要

Disclosed is a group III nitride semiconductor device containing a gallium nitride semiconductor film having good surface morphology. A group III nitride semiconductor optical device (11a) comprises a group III nitride semiconductor supporting body (13), a GaN semiconductor region (15), an active layer (17) and a GaN semiconductor region (19). A major surface (13a) of the group III nitride semiconductor supporting body (13) is nonpolar, being inclined to the reference plane Sc which is perpendicular to the reference axis Cx. The reference axis Cx extends in the direction of the c-axis of the group III nitride semiconductor. The GaN semiconductor region (15) is formed on the semipolar major surface (13a). A GaN semiconductor layer (21) of the GaN semiconductor region (15) is composed of, for example, an n-type GaN semiconductor, and silicon is added into the n-type GaN semiconductor. When the oxygen concentration of a GaN semiconductor layer (23) is not less than 5 × 1016 cm-3, the active layer (17) continuously grown on a major surface of the GaN semiconductor layer (23) has good crystal quality.