Epitaxial growth of Si films on CaF2/Si structures with thin Si layers predeposited at room temperature

Abstract

Heteroepitaxial growth of vacuum-evaporated Si films on CaF2/Si structures has been investigated. In order to prevent surface reaction between deposited Si and the underlying CaF2 films at high temperatures, a thin Si layer is in situ deposited at room temperature onto the CaF2 surface prior to deposition of Si at 800 °C. It has been shown from morphological and ion channeling studies that the thin predeposited Si layer, less than 10 nm in thickness, is useful to prevent the surface reaction without destroying the epitaxial growth, and that this technique is applicable to both (111) and (100) oriented substrates. The early stage of the growth is also studied. It has been found that the majority of the predeposited Si layer is not aligned to the substrate orientation even after a thick film has grown epitaxially. A possible model for the epitaxial growth is discussed.