THE IMPACT AND REDUCTION OF CDZNTE SUBSTRATE DEFECTS ON OMVPE HGCDTE EPILAYER PERFORMANCE

DEFECTS IN THE CDTE FAMILY OF SUBSTRATES ARE OF CRITICAL IMPORTANCE WHEN GROWING EXPITAXIAL FILMS OF HGCDTE BY LPE, OMVPE OR MBE. PRECIPITATES, DISLOCATIONS, AND SUBGRAIN STRUCTURE IN SUBSTRATES DEGRADE THE SURFACE MORPHOLOGY AND MICROSTRUCTURE OF EXPITAXIAL LAYERS, LEADING TO DECREASED EPILAYER YIELDS AND POOR IR DETECTOR PERFORMANCE. MISMATCH BETWEEN THE LATTICE PARAMETERS OF SUBSTRATE AND EPILAYER CAN LEAD TO HIGHER DISLOCATION DENSITY, POOR SURFACE MORPHOLOGY, AND STRAIN IN THE EPILAYER. PHASE I WILL QUANTIFY THE EFFECT ON CDZNTE SUBSTRATE LATTICE STRAIN, SUBGRAIN STRUCTURE AND MISMATCH ON THE PROPERTIES OF HGCDTE EPILAYERS GROWN BY OMVPE AND ON SUBSEQUENT IR DETECTOR YIELDS. PHASE II IS EXPECTED TO BROADEN THE SCOPE OF THE STUDY TO DETERMINE THE ROLES OF TE PRECIPITATES, ETCH PIT DISTRIBUTION, MICROTWINNING, AND PURITY IN SUBSTRATEEPILAYER INTERACTIONS.