ULTRAFAST PHOTOCONDUCTORS FROM LOW-TEMPERATURE MOCVD-GROWN GAAS AND INGAAS EPITAXIAL LAYERS

GaAs and InGaAs epitaxial layers were grown by Metal-Organic Chemical Vapor Deposition at Low substrate Temperatures (LT-MOCVD). The layers, grown at temperatures below 430 degrees C were semi-insulating. Trans mission electron microscopy images reveal uniformly distributed 3-10 n m size clusters which consist, most probably, of zinc. Photodetectors fabricated from those layers feature nonlinear photocurrent versus opt ical power dependence. The nonlinearities are explained in terms of el ectric field redistribution. The nonlinear photoconductive correlation measurements show that excess carrier lifetimes are in the range of 2 0-50 ps.