Temperature Dependence of the Photoluminescence Linewidth of In0.2Ga0.8As Quantum Wells on GaAs(311) Substrates

We have studied the photoluminescence (PL) properties of strained In0.2Ga0.8As/GaAs quantum well (QW) structures grown by molecular beam epitaxy on (311)-oriented substrates. Special attention has been paid to the PL linewidth measurements in terms of the full width at half maximum (FWHM). We obtained the FWHM temperature dependence in the range of 5-250 K and compared it to measurements done in unstrained AlGaAs/GaAs(100) QW structures. The linewidth broadening of the unstrained system could be satisfactorily explained by means of a model which takes into account the exciton-acoustic phonon and exciton-LO phonon interactions. This model doesn't describe adequately the experimental data from the InGaAs/GaAs system. Remarkable differences, such as the dependence of the linewidth on the dimensions of the wells were found. We think that the additional effects to which the InGaAs QWs are subjected, namely, strain and built-in electric fields, are the origin of the completely different behavior of the linewidth broadening.