The epitaxial growth and properties of p-type silicon on spinel using a dual-rate deposition technique

Abstract

1.5 μm thick silicon on spinel films with hole mobilities equivalent to bulk silicon can be grown by utilizing a dual-rate deposition technique. An initial deposition rate of 2 μm/min is used to obtain rapid surface coverage of the spinel substrate, in order to suppress the contamination reactions at the silicon-spinel interface. After surface coverage is complete the deposition rate is decreased to 0.3μm/min in order to improve the crystalline perfection of the deposited film. By using the dual-rate technique combined with high purity silane source gas, as-deposited mobilities equivalent to bulk silicon can be obtained at hole concentration as low as 5 X 10 15/cm 3, with a decrease in mobility on only 10% during thermal oxidation. The deposition temperature has a significant effect on the properties of the silicon on spinel films, with films deposited below 1085 °C having very high resistivities, while films deposited at ⋍ 1150 °C have large changes in properties during thermal oxidation, because of heavy autodoping. The optimum deposition temperature involves a compromise between these two extremes, both in temperature, and in film properties.