Sapphire surface preparation for the growth of silicon layers by molecular-beam epitaxy

Abstract

The structural perfection and surface morphology of sapphire substrates vacuum-annealed at atomic Si flux densities from 5 × 1015 to 1 × 1016 at/(cm2 s) have been studied by electron diffraction, X-ray diffraction, and atomic force microscopy. The results demonstrate that, after annealing in the range 1160–1330°C, the sapphire has a smooth, single-crystal surface, which enables the growth of twin-free silicon epilayers at 600–700°C.