Molecular-beam epitaxial growth and characterization of GaAs on epitaxial CoSi2 films on Si(111)

Abstract

Using molecular-beam epitaxy, we have studied growth of GaAs on epitaxial CoSi2 films on Si(111) substrates. The surface morphology of 1-μm-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 CoSi2 than on Si(111). Secondary ion mass spectroscopy and transmission electron microscopy (TEM) indicated abrupt GaAs/CoSi2 and CoSi2/Si interfaces, suggesting excellent thermal stability of CoSi2. TEM revealed that the defect structure in GaAs was dominated by microtwin plates generated at the interface. The increase in pinhole size in CoSi2 was drastically reduced if the substrate was heated in arsenic flux. The GaAs surface was found to be terminated with As atoms. The photoluminescence intensity of GaAs/CoSi2 was only a factor of 2 lower than that of GaAs/GaAs. The measured Rutherford backscattering spectroscopy minimum channeling yield (χmin) was 0.094. GaAs/CoSi2/Si transistorlike devices were made, but no transistor action was observed due to poor interfacial quality of the GaAs/CoSi2 junction. The ideality factor and barrier heights were 2.5 and 0.45 eV for the GaAs/CoSi2 junction, and 1.25 and 0.635 eV for the CoSi2/Si junction.