Growth of CdTe films on silicon by molecular beam epitaxy

Abstract

Results of initial attempts to grow cubic-phase CdTe films on (111) and (100) Si substrates by molecular beam epitaxy are reported. Substrate temperatures in the range 200–400 °C were employed along with deposition rates of 1–9 Å/s. Films grown at temperatures below 300 °C exhibited streaked x-ray diffraction patterns which contained extra hexagonal-phase features. Sharp cubic-phase epitaxy was obtained for CdTe films grown on (111) Si substrates at 330–350 °C. Similar depositions on (100) Si substrates also produced epitaxial CdTe films. However, the (100) epilayers displayed unusual x-ray diffraction patterns which are suggestive of twin formation. Nomarski micrographs revealed the epitaxial CdTe films to be uniformly free of voids and microcracks despite the large difference in lattice constant and thermal expansion coefficient for these materials.