Effects of the inclination direction of vicinal m-plane sapphire substrates on the crystal quality of m-plane GaN film

Herein is a discussion of how the structural and optical properties of m-plane GaN (m-GaN) films are affected by the inclination direction of vicinal m-plane sapphire substrate. The m-GaN films were grown on three different types of substrates inclined toward the a-axis direction, the c-axis direction, and with no inclination. We found that m-GaN film grown on an m-plane sapphire inclined in the a-axis direction showed the highest quality with a smooth surface and a low stacking fault density. A model is proposed that shows how the surface step of a substrate can reduce the generation of stacking fault in m-GaN film.

► Effects of the inclination direction of vicinal m-plane sapphire substrates were discussed. ► m-Plane sapphire inclined in the a-axis direction showed the highest quality m-plane GaN. ► BSFs are compensated by a step on the inclined substrate in the a-axis direction.