Optically induced far-infrared absorption from residual acceptors in as-grown GaAs

Abstract
Far-infrared Fourier transform spectroscopy has been applied to study residual shallow acceptors in as-grown semi-insulating GaAs. Secondary optical excitation into the EL2 absorption band has been used to create a nonequilibrium hole population to neutralize the acceptors. Optically induced absorption spectra from carbon and zinc acceptors have been observed. The dependence of these spectra on the secondary illumination is studied. A comparison is made with electronic Raman spectra recorded from the same samples.