Raman scattering as a quantitative tool for residual acceptor assessment in semi-insulating GaAs

Electronic Raman scattering has been employed to characterize as-grown semi-insulating GaAs. All samples investigated exhibit electronic Raman signals from residual acceptors (carbon and/or zinc). The intensity of these signals varies by more than one order of magnitude from sample to sample. Comparative local vibrational mode measurements to determine the carbon content suggest a quantitative correlation with the carbon acceptor concentration. The detection limit for this Raman characterization is well below 1015 acceptors/cm3 for samples cut from 500-μm-thick standard wafer material. Spatially resolved studies show that the scattering intensity fluctuates significantly across a 2-in. GaAs wafer.