The influence of an ultrathin pseudomorphic interface control layer of Si on the growth of SrF2 on GaAs

We deposited Si on GaAs (100) and (111) at 450 degrees C to 550 degrees C. On GaAs(100)-(2 x 4) and -(4 x 2) the Si grows in bilayer mode with single domain (1 x 2) and (2 x 1) reconstructions, respectively. The films are pseudomorphic up to a critical thickness of 10ML. SrF2, deposited on Si/GaAs(100) at 550 degrees C, grows with a rough surface due to (111) facets. On GaAs(111) A and B the Si grows epitaxially without any superstructure. The films are pseudomorphic up to a critical thickness of 5ML. It is remarkable that SrF2 deposited at 550 degrees C on Si/GaAs(lll)grows in A-type with a high epitaxial duality, whereas SrF2 on bulk Si grows in B-type.