Evidence for the influence of interfacial atomic structure on electrical properties at the epitaxial CaF sub 2/Si(111) interface.
01 January 1988
The atomic structure at the epitaxial CaF sub 2/Si(111) interface has been determined using high resolution electron microscopy. As-grown layers reveal direct Ca-Si bonding at the interface, with eight-fold coordinated Ca atoms. Fluorine is preferentially removed from the interface during a rapid thermal anneal leaving five-fold coordinated Ca atoms.
No evidence for direct F-Si bonding is observed. Removal of F results in a dramatic improvement in the electrical properties of the interface. The measured interface state density is reduced from >~ 10 sup (13) cm sup (-2) to <~ 10 sup (11) cm sup (-2).