INVESTIGATIONS OF POSITRON LIFETIMES IN INP WITH A PULSED POSITRON BEAM

Indium Phosphide layers grown by gas source Molecular Beam Epitaxy, (MBE) have been studied by positron lifetime spectroscopy using the recently modified pulsed positron beam in Munich. The as-grown samples are known to be phosphorous rich and contain a high concentration of vacancy-type defects. On annealing, phosphorous precipitates are formed and the concentration of free volume defects increases. Positron lifetime spectroscopy has identified the grown in defects to be indium vacancies at a concentration around 10(18) cm(-3). The dominant defects after annealing exhibit a positron lifetime characteristic of divacancies and are present at concentrations in excess of 5 x 10(19) cm(-3).