ALLOY COMPOSITION AND TEMPERATURE-DEPENDENCE OF THE DIRECT ENERGY-GAPIN ALXGA1-XAS

An empirical model is proposed to analyze the variation of the direct energy gap E-0 with temperature and alloy composition in the system Al xGa1-xAs. The E-0(T) curve for pure A;As was found to be slightly lowe r than that reported for a high impurity concentration sample. The adj ustable parameters obtained for this compound can be related to its av erage optical phonon energy and lattice thermal dilation coefficient. For the alloys, one of these parameters can also be related to the bro adening observed in the line shape of the direct E-0 exciton due to el ectron-phonon interaction. (C) 1997 Elsevier Science Ltd. All rights r eserved.