GAAS IMPLANTED WITH SILICON AND CARBON - ELECTRICAL AND OPTICAL CHARACTERIZATION

Semi-insulating GaAs samples co-implanted with silicon and carbon have been studied by electrical and optical measurements in order to evalu ate the compensation level obtained with different post-implant therma l treatments. A triple implant of silicon at different energies and do ses has been performed so as to get a carrier concentration profile ha ving a flat region. Carbon has been implanted at an energy so as to ge t the peak atomic concentration in the middle of the multiple silicon implant; four different carbon doses have been selected. Carbon has be en confirmed to be an effective compensator of silicon, particularly i f it is implanted in already activated Si-implanted GaAs: compensation efficiencies of the order of 60-70% are reached. The main feature of the photoluminescence spectra is an intense band whose intensity and p eak energy depend on the implanted carbon dose. A simple relation betw een the peak energy of this band and the compensation is found which m ay provide a simple method to evaluate the compensation itself, once a calibration curve has been obtained from electrical measurements.