Characterization of Planar Semipolar Gallium Nitride Films on Sapphire Substrates

Abstract

Specular, planar semipolar gallium nitride films were grown by hydride vapor phase epitaxy. Planar films of (1013) and (1122) GaN have been grown on (1010) m-plane sapphire. The in-plane epitaxial relationship for (1013) GaN was [3032]GaN ∥[1210]sapphire and [1210]GaN ∥[0001]sapphire. The in-plane epitaxial relationship for (1122) GaN was [1121]GaN ∥[0001]sapphire and [1100]GaN ∥[1210]sapphire. The (1013) films were determined to have N-face sense polarity and a threading dislocation density of 9×108 cm-2. The (1122) films have Ga-face sense polarity and have a threading dislocation density of 2×1010 cm-2. The basal plane stacking fault density was 2 ×105 cm-1 for both orientations. The RMS roughness of the films was under 10 nm for a 5 ×5 µm2 area.