Analysis of secondary phases in InSbBi thin films

The secondary phases formed during the epitaxial growth of InSbBi by metal-organic vapor-phase epitaxy is reported. The material was grown on InSb and GaAs substrates at 455 degrees C and was characterised using scanning electron microscopy (SEM), cross-sectional transmission electron microscopy (TEM) and X-ray diffraction. The formation of secondary phases was found to be critically dependent on the V/III ratio. A V/III ratio slightly below stoichiometry lead to InBi and In2Bi phases forming on the surface, whereas a V/III ratio slightly above stoichiometry produced BiSb phases. Cross-sectional TEM revealed the formation of large Bi inclusions within layers grown on InSb substrates. The Bi inclusions ranged in size from 0.5 to 1 mu m and were distributed throughout the epilayer. Bi-Ga inclusions were observed in the case of layers grown on GaAs substrates. (C) 1999 Elsevier Science B.V. All rights reserved.