Surfactant effects of Sn on [formula omitted] heteroepitaxy by molecular beam epitaxy

Abstract

Surfactant effects of Sn on SiGe Si heteroepitaxy by molecular beam epitaxy are investigated. The Sn adlayer strongly segregates onto both Si and Ge overgrowth layers. Both, observations of the reflection high energy electron diffraction and the transmission electron microscope indicate that Sn facilitates the formation of SiGe islands which is opposite to the effect reported for other surfactants. This effect leads to the formation of large islands. As a result, the critical thickness for misfit dislocations is reduced by Sn-mediated growth. However, surface segregation of Ge can be suppressed by using Sn. The surfactant effect of Sn on Ge island formation is discussed.