Defects with a mound structure were formed, during Si epitaxy on (001) Si substrates, when using low-pressure chemical vapour deposition at 700C. This was true even if the surface was atomically clean. The structure of the mound was that of a quadrangular pyramid, in which high-density {111} twins existed. The formation of the defects was attributed to the high pressures of SiH4 and H2. Epitaxial growth of high perfection was suppressed, by a high pressure of the H2 ambient, because H suppressed the decomposition of SiH4 and the surface migration of atoms. At the same time, a growth front that can provide the high deposition rate was preferred under the conditions of high SiH4 pressure. Crystalline structures with {111} twins were favourable for obtaining a high growth rate, because terraces and steps formed at the growth front. The mounds formed due to the higher deposition rate on the edge of {111} twins than that on the (001) plane.

Mechanism of Defect Formation during Low-Temperature Si Epitaxy on Clean Si Substrate I.Mizushima, M.Koike, T.Sato, K.Miyano, Y.Tsunashima: Japanese Journal of Applied Physics - 1, 1999, 38[4B], 2415-8