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 evaluate the compensation level obtained with different post-implant thermal treatments. A triple implant of silicon at different energies and doses has been performed so as to get a carrier concentration profile having a flat region. Carbon has been implanted at an energy so as to get the peak atomic concentration in the middle of the multiple silicon implant; four different carbon doses have been selected. Carbon has been confirmed to be an effective compensator of silicon, particularly if 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 peak energy depend on the implanted carbon dose. A simple relation between the peak energy of this band and the compensation is found which may provide a simple method to evaluate the compensation itself, once a calibration curve has been obtained from electrical measurements.