Optical properties of InAlGaAs quantum wells: Influence of segregation and band bowing

Knowledge of the quaternary InAlGaAs material system is very limited for the composition range relevant for growth on GaAs substrates. We report on the characterization and modeling of InAlGaAs quantum wells with AlGaAs barriers, grown pseudomorphically on a GaAs substrate with molecular beam epitaxy. The quantum wells are characterized with photoluminescence, and the measured transition energies are modeled taking into account the influence of In segregation on the shape of the well potential. From the modeling we deduce a relation for the low temperature band gap of unstrained In-x(AlyGa1-y)(1-x)As, for 0 less than or equal to x,y less than or equal to 0.20. The measured linewidths of the luminescence peaks are in agreement with the broadening expected from random alloy fluctuations and well width fluctuations with an effective interface roughness of 1.1 ML. (C) 1999 American Institute of Physics. [S0021-8979(99)00617-9].