THE GROWTH OF INP1-XSBX BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION

InP1-xSbx was grown by metalorganic chemical vapor deposition under a variety of conditions. The V/III vapor phase ratio was varied from 327 to 12 over a temperature range of 450-525-degrees-C, at pressures of 77 to 660 Torr and growth rates of 0.30 to 2.0 mum/h. For some samples, the V/III vapor phase ratio was optimized for InP1-xSbx lattice matched to InAs to give smooth morphologies and lattice matching with a minimized variation of composition versus changes in the TMSb/(TMSb + PH3) ratio. Examination by transmission electron microscopy indicates that the materials are not single phase, but have undergone a spinodal decomposition, which is consistent with thermodynamic calculations. When our specimen compositions are corrected for strain relaxation, the infrared photoluminescence measurements indicate a lower energy photoluminescence peak for these materials than had been previously reported in the literature. Infrared absorption and photoconductivity measurements indicate no sharp band edge as would be expected for a direct gap semiconductor. The observed broad spectra are consistent with alloy decomposition.