Characterization of secondary phases formed during MOVPE growth of InSbBi mixed crystals

Secondary phases, formed during the growth of InSbBi, a III-V compound with potential for infrared applications in the 8-12 mu m range, are reported. Layers were prepared by atmospheric pressure metal-organic vapour-phase epitaxy at 455 degrees C in a horizontal quartz reactor. The source materials used were trimethylindium (TMIn), trimethylantimony (TMSb), and trimethylbismuth (TMBi). Scanning electron microscopy and X-ray diffraction spectra showed the formation of extra phases on the surfaces of the layers. The compositions of these condensed phases were influenced by the V/III ratio at the growth interface. Bi precipitates were observed by cross-sectional transmission electron microscopy for layers grown on InSb substrates. Attempts to grow InSbBi on GaAs substrates produced InAsSb layers. The As composition showed a dependence on the availability of Bi, increasing from 7.5 to 26 mol% InAs when increasing the Bi/V ratio from 0.04 to 2%. The incorporation of As has been related to the formation of Bi-Ga inclusions at the GaAs interface. (C) 2000 Elsevier Science B.V. All rights reserved.