Conduction band offset ratio of the (In,Ga)As/GaAs system and (In,Ga)As alloy properties

The strained conduction band offset ratio Q(c) is determined for InxGa1-xAs/GaAs quantum wells, with various indium concentrations, x between 0.1 and 0.5 and various well thicknesses: from the analyses of thermally-detected optical absorption results. Q(c) is chosen as an adjustable parameter in the models used to describe the quantum well levels. The best fits of the calculated excitonic energies to those measured from the spectra give a value of Q(c), equal to 0.64 +/- 0.02, independent of x in the range investigated. A simple model is also used to obtain Q(c) from the electronic properties of the (In,Ga)As alloy, grown on GaAs. A constant value of Q(c) in excellent agreement with that reported above is found. The bowing assigned to the valence band maximum is 25% of the total alloy band gap bowing. (C) 1997 Elsevier Science S.A.