Comparative Study of the Characteristics of the Basal Plane Stacking Faults of Nonpolar a−Plane and Semipolar (1122) Ga

Nonpolar (1120) and semipolar (1122) GaN are grown on r−plane and m−plane sapphire by MOCVD to investigate the characteristics of basal plane stacking faults (BSFs). Transmission electron microscopy reveals that the density of BSFs for the semipolar (1122) and nonpolar a−plane GaN template is 3×10⁵ cm⁻¹ and 8×10⁵ cm⁻¹, respectively. The semipolar (1122) GaN shows an arrowhead−like structure, and the nonpolar a−plane GaN has a much smoother morphology with a streak along the c−axis. Both nonpolar (1120) and semipolar (1122) GaN have very strong BSF luminescence due to the optically active character of the BSFs.