Growth of low dislocation density CdTe films on hydroplaned CdTe substrates by molecular beam epitaxy

Abstract

A systematic study of CdTe film growth by molecular beam epitaxy (MBE) on hydroplaned (111)A and (111)B CdTe substrates is discussed. Substrate preparation prior to growth involved chemical etching techniques, rather than sputtering in UHV, in order to maintain the integrity of the hydroplaned surface. A range of substrate temperature during growth was investigated. X-ray diffraction, UV reflection, and transmission electron diffraction measurements were employed to evaluate the structural quality of the CdTe films. Bright and dark field transmission electron microscopy was used to determine film dislocation densities. An entirely different film growth morphology was observed on the (111)A versus (111)B substrate surfaces for the range of temperatures and growth rate employed. Growth of high quality, low dislocation density, twin-free CdTe films was achieved on hydroplaned (111)A CdTe substrates at 250 °C.