Strain Relief in SrF2 Epitaxial Films on Si(111) Substrates

Abstract

ABSTRACTMolecular beam epitaxial (MBE) growth condition of SrF2 directly on Si(111) substrates has been optimized in terms of both Xmin and the surface morphology. Lattice distortion measurements were carried out with ion channeling along off-normal channeling directions in the strained layers grown at the optimal condition. The relationship of residual strain vs. film thickness for SrF2 on Si(111) was provided by the first time. The experimental data demonstrated a special thickness in this relation, at which the derivative of strain vs. film thickness changes its sign. This unique behavior was understood as the result of competition between the large lattice mismatch and the large thermal mismatch between SrF2 and Si.