Photoluminescence of Al_0.4Ga_0.6As/GaAs quantum well structures prepared by molecular beam epitaxy

The effect of growth conditions, in particular the substrate temperature, on the quality of Al0.4Ga0.6As/GaAs quantum well heterostructures grown by molecular beam epitaxy was investigated. Characterization by low temperature photoluminescence indicates that the quality of the AlxGa1 - xAs confining layer is optimized at 720 °C; above 720 °C it becomes very difficult to maintain sufficient arsenic coverage on the surface because of rapid arsenic desorption. The quality of the quantum wells is dominated by the interfacial properties which are dependent on the quality of the AlxGa1 - xAs and to some extent on the quality of the GaAs. Our experiments show that a substrate temperature of 720 °C also optimizes the quantum wells. The photoluminescence spectra of the Al0.4Ga0.6As layers show excitonic processes with a width of 7 meV. © 1984.