Epitaxial growth of CdTe films on GaAs-buffered (001) Si substrates by metal organic chemical vapor deposition

Abstract

Epitaxial (001) CdTe thin film was successfully grown on a (001) Si substrate using an atomically smooth, thin (2nm) GaAs buffer layer deposited using the metal organic chemical vapor deposition method. High-resolution transmission electron microscopy studies revealed a periodic distribution of dislocations due to lattice mismatch along the interfaces between CdTe film, GaAs buffer layer, and Si substrate. Most of the dislocation cores were located inside the GaAs buffer layer or at the interface between the CdTe and GaAs layers, indicating that GaAs buffer layer originally coherent to Si, was fully relaxed during the CdTe layer growth. The thin GaAs buffer layer effectively absorbed any strain coming from the large lattice mismatch between a CdTe layer and a Si substrate by forming an array of structural defects in the GaAs layer, which permitted epitaxial growth of CdTe on the Si substrates.