Improving the Quality of a Heteroepitaxial CaF sub 2 Overlayer by Rapid Post Annealing

We show that post anneals of short duration at high temperature can markedly improve the quality of CaF sub 2 films grown by molecular beam epitaxy (MBE) on Si(100). Anneals at 1100C for 20 sec in an Ar ambient improved sub (X) sub (min), the ratio of backscattered 1.8 MeV He sup 4 ions in the aligned to random direction, from as-grown values of .07 to post post-anneal values of .03 to .045. This is the best sub (X) sub (min) yet reported for the CaF sub 2:Si system. The post-annealed films also show improved resistance to chemical etching and mechanical stress, and increased dielectric breakdown voltages.