Characterization of alloy composition in Ga1-xAlxAs/GaAs structures: comparison of photovoltage, X-ray, SIMS and RHEED techniques

Abstract A comparative study of techniques for the characterization of alloy composition in Ga 1- x Al x As/GaAs single and multilayer structures has been carried out. Good agreement ( x ± 0.015) is demonstrated between double-crystal X-ray diffraction and photovoltage spectroscopy measurements using the generally accepted calibration of Casey and Panish. A slightly modified form of the band gap versus composition curve is presented which further improves the agreement to x ±0.005. Profiling conditions achieving linear SIMS Al profiles are reported, yielding compositions in agreement with PVS and X-ray within x +-0.01 (when calibrated at a single composition). A systematic discrepancy between results from the above techniques and in-situ RHEED oscillation measurements is reported.