Surface texture and structure of ZnO films synthesized by off-axis sputtering deposition

Abstract

Morphology and structure of ZnO films deposited on (0001) sapphire and glass substrates by off-axis sputtering were investigated at various temperatures and pressures. All films show highly textured structures on glass substrates and epitaxial growth on sapphire substrates. The full width at half-maximum of theta rocking curves for epitaxial films is less than 0.5°. In textured films, it rises to several degrees. The trend of surface textures in films grown at low pressures is similar to those grown at high temperatures. A morphology transition from large well-defined hexagonal grains to flat surface was observed at a pressure of 50 mtorr and temperature of 550°C. The experiment results are explained by the transport behavior of depositing species.

Low temperature epitaxy of reactively sputtered ZnO on sapphire

“…A similar improvement in quality with pressure was previously reported for sputtered ZnO. 28 Energetic particle bombardment of the substrate and growing film generally occurs in sputtering systems under these conditions, and is known to enhance epitaxy. [4][5][6] The other effect proposed here is enhanced Zn adatom diffusivity.…”