Epitaxial relations in alkaline earth fluoride–semiconductor systems

Previous studies of epitaxial fluoride–semiconductor systems have demonstrated that parameters such as substrate temperature during film growth and substrate orientation strongly affect epitaxial quality. The role of a good lattice match in these systems has not been clearly resolved, however. In this study we have performed Rutherford backscattering/channeling measurements on a variety of fluoride–semiconductor systems having a wide range of lattice mismatch. The results demonstrate that the largest misfit system [BaF2/Ge(111) with a 9.6% mismatch] supports two orientations of BaF2 crystallites with respect to the Ge substrate, whereas smaller misfit systems support only one orientation. This result is related to our previous finding of a novel incommensurate interface in this epitaxial system.