MBE growth and characterization of GaAS on Epitaxial CoSi sub 2 films on Si(111).

Using molecular beam epitaxy, we have studied growth of GaAs on epitaxial CoSi sub 2 films on Si(111) substrates. The surface morphology of 1micron thick layers was comparable to GaAs grown on GaAs(111) under similar conditions. Also, the quality of GaAs was, in general, a little better on CoSi sub 2 than on Si(111). Secondary ion mass spectroscopy and transmission electron microscopy (TEM) indicated abrupt GaAs/CoSi sub 2 and CoSi sub 2 /Si interfaces suggesting excellent thermal stability of CoSi sub 2. TEM revealed that the defect structure in GaAs was dominated by microtwin plates generated at the interface. The increase in pinhole size in CoSi sub 2 was drastically reduced if the substrate was heated in arsenic flux. The GaAs surface was found to be terminated with As atoms.