Photoluminescence of high-quality AlGaAs layers grown by molecular-beam epitaxy

We report a photoluminescence study of high-purity AlxGa1−xAs layers grown by molecular-beam epitaxy over the 0⩽x⩽0.295 composition range. The intense excitonic line dominates in the photoluminescence spectra of the layers. The full width at half maximum of the excitonic line is in excellent agreement with values calculated by Lee and Bajaj [J. Appl. Phys. 73, 1788 (1993)] for perfectly random alloys, and in the spectra of the layers with AlAs fractions of x=0.15 and x=0.209 it equals to 1.24 and 1.48 meV, respectively. A linear dependence of the exciton line intensity on excitation power evidences negligible concentration of nonradiative recombination centers in the layers.