Epitaxial growth of high quality ZnO:Al film on silicon with a thin γ-Al2O3 buffer layer

Abstract

ZnO:Al thin films were grown epitaxially on $\mathrm{epi}\mathrm{-\gamma -}{\mathrm{Al}}_2{\mathrm{O}}_3/\mathrm{Si}$ (111) substrates by rf sputtering and pulsed laser deposition. The $\mathrm{\gamma -}{\mathrm{Al}}_2{\mathrm{O}}_3$ buffer layer was deposited on Si (111) at a low substrate temperature of 500 °C using the metalorganic chemical vapor deposition method. Reflection high energy electron diffraction and x-ray diffraction measurements indicated a near alignment of the ZnO:Al epilayer on $\mathrm{\gamma -}{\mathrm{Al}}_2{\mathrm{O}}_3/\mathrm{Si}$ (111) as compared to those grown directly on Si (111). Atomic force microscopy results of the films $\mathrm{ZnO:Al}\mathrm{/\gamma -}{\mathrm{Al}}_2{\mathrm{O}}_3/\mathrm{Si}$ (111) deposited by pulsed laser deposition revealed a smoother surface in comparison with the films deposited by rf sputtering. The M band observed in the photoluminescence spectra of the films deposited by laser ablation suggests that high quality epitaxial $\mathrm{ZnO:Al}\mathrm{/\gamma -}{\mathrm{Al}}_2{\mathrm{O}}_3/\mathrm{Si}$ (111) films can be deposited by pulsed laser deposition.