Epitaxial n-ZnO on p-Si with native SiOx reduced by Al buffer

RF sputtering was employed to deposit n-type zinc oxide epitaxial thin films on p-type silicon substrates to form p-i-n diodes. A buffer layer of crystalline metal oxide was introduced by redox reaction between an aluminum layer and the native SiO$_{2}$. The aluminum layer was sputtered to various thicknesses and then annealed in situ for different times. The epitaxial relations follow (111) $_{Si}$//(0001) $_{ZnO}$ and [110] $_{Si}$//[11$\bar{2}$0] $_{ZnO}$, though certain degree of mosaicity was observed wavering around the [11$\bar{2}$] $_{Si}$ axis. Cross-sectional TEM observations of the interfaces, x-ray crystallography via $\omega$-2$\theta$ and rocking scans in regards to the perfection of the structures and orientations are agreeable. The current-voltage characteristics of the p-i-n diodes show promising outlooks for light emitting and photovoltaic applications.