Correlation between optical properties and barrier composition in InxGa1-xP/GaAs quantum wells

In this work high structural and optical quality InxGa1-xP/GaAs quantum wel ls in a wide range of thicknesses have been successfully grown on GaAs subs trates by low temperature atomic layer molecular beam epitaxy. We demonstra te that compositional fluctuations in the barrier alloy are responsible for the inhomogeneous broadening and spatial localization effects observed in the excitonic recombination, the influence of quantum well width fluctuatio ns being negligible in comparison. An important change of the optical trans ition energies in these quantum wells is observed when tuning a 10% In-Ga r atio in the alloy around the lattice match composition (x = 0.48). This cha nge is related to the barrier band gap variation and the intrinsic characte ristics of the InGaP/GaAs heterostructure: different exciton binding energy from tensile to compressive strain in the barrier, and a possible dependen ce of the conduction band offset on the In composition. (C) 1998 American I nstitute of Physics. [S0021-8979(98)04023-7].