(111)-Oriented Zn3N2 Growth on a-Plane Sapphire Substrates by Molecular Beam Epitaxy

Abstract

(111)-oriented Zn3N2 thin films were grown on a-plane (1120) sapphire substrates by plasma-assisted molecular beam epitaxy. Zn3N2/sapphire exhibits orientational relationships of out-of-plane <111>∥[1120] and in-plane almost <110>∥[0001] and <101>∥[0001]. These specific orientations result from similar surface configurations of N atoms in Zn3N2 and Al atoms in sapphire at the interface. Under the optimum growth conditions, the film showed a full width at half maximum of 185 arcsec for an X-ray (222) diffraction rocking curve and a root-mean-square roughness of 8.5 Å in an atomic force microscope image. These results suggest that a-plane sapphire is a suitable heteroepitaxial substrate for high-quality Zn3N2 thin films.