Growth of (100) oriented CdTe on Si using Ge as a buffer layer

Abstract

Epitaxial (100) CdTe layers have been grown on (100) oriented Si substrates by atmospheric pressure organometallic vapor phase epitaxy using thin Ge as a buffer layer. A very thin native oxide layer may be present on Si substrates after etching in a HF solution and this can be removed by passing GeH4 gas over Si at 450 °C. The removal of this oxide takes several minutes depending on the oxide layer thickness and reactor conditions. For the CdTe layers grown on Ge/Si substrates, single-crystal (100) CdTe can be obtained at growth temperatures higher than 420 °C. For growth temperatures below 420 °C, a mixture of both (100) and (111) oriented CdTe was present. The x-ray full width at half-maximum of the (400) peak was 780 arcsec for a 3.1-μm-thick CdTe layer grown at 450 °C with a Ge buffer. Although all the layers had antiphase domains, single-domain CdTe can be grown on (100)Si misoriented towards [110]. This result presents an alternative for nucleating CdTe on Si without a GaAs buffer layer.