The Effect of Rapid Thermal Annealing of Heteroepitaxial Structures

We have found that a rapid thermal anneal (RTA) is useful for improving the quality of variety of heteroepitaxial structures: CaF2/Si(100) and (111), CaF2/CoSi2/Si(111), and Si(100) on sapphire (1102) (SOS). In all cases, and RTA having a peak temperature near the melting point of the top heteroepitaxial layer and lasting as least several seconds improves the layer structurally. The backscattering minimum yield near the surface (Xmin) measured by Rutherford backscattering and channeling improves in all cases to near its theoretical value. Transmission electron microscopy studies are shedding light on the nature of the changes in the films brought about by RTA. In particular, the volume of microtwins in SOS layers is seen to fall dramatically throughout the film. High resolution TEM is being used to probe the effect of RTA on the interfacial structure of these systems. Anomalies in the transport in thin CoSi2 films after RTA may be due to diffuse scattering caused by surface roughness induced by the RTA. A model which we have proposed to account for the SOS results is based on isothermal solid phase epitaxial regrowth from the epitaxially oriented material in the as-grown film. This model may be applicable to the other heteroepitaxial systems we have studies as well.