Photoreflectance of GaAs and Ga0.82Al0.18As at elevated temperatures up to 600thinsp;deg;C

摘要

We report a modulation spectroscopy experiment on GaAs and Ga0.82Al0.18As at elevated temperatures. Using the contactless electromodulation method of photoreflectance, the direct gaps (E0) of these materials have been observed from 77 K to 600thinsp;deg;C. The latter temperature is comparable to molecular beam expitaxy, metalorganic chemical vapor deposition, growth temperatures, etc. Our results are at the highest temperature yet reported forE0(GaAs) in a reflectance experiment and the first observation ofE0(Ga1minus;xAlxAs) at elevated temperatures. From the latter, the Varshni coefficients lsqb;Physica34, 149 (1967)rsqb; for Ga0.82Al0.18As were determined.