Epitaxial growth of alkaline earth fluorides on semiconductors

Abstract The growth and characterization of epitaxial alkaline earth fluorides (CaF 2 , SrF 2 , BaF 2 and mixtures thereof) on semiconductors are reviewed. Various mixed and unmixed fluorides have been found to grow epitaxially on several semiconductors, most notably silicon, InP and germanium. Parameters which strongly affect the epitaxial quality include the substrate temperature during deposition and the substrate orientation. The degree of lattice matching plays a much smaller role in determining the epitaxial quality. In one fluoride/semiconductor system (BaF 2 /Ge(111)) there is a novel interface which exhibits neither misfit dislocations nor coherence, despite a large lattice mismatch. The fluorides show promise as epitaxial insulating layers in semiconductor/insulator/semiconductor heterostructures.