Line-shape analysis of the reflectivity spectra of GaAs/(Ga,Al)As single quantum wells grown on (001)- and (311)-oriented substrates

The reflectivity line shape of single quantum wells is calculated as a function of the thickness of the sample structure near the excitonic resonances. By direct comparison between the calculation and the experimental reflectivity we can deduce the oscillator strength of 1s and 2s excitons in the case of GaAs/${\mathrm{Ga}}_{0.7}$ ${\mathrm{Al}}_{0.3}$As single quantum wells grown on (001)-oriented substrates. GaAs/${\mathrm{Ga}}_{0.81}$ ${\mathrm{Al}}_{0.19}$As single quantum wells grown on (311)-oriented GaAs substrates with thickness ranging from 5 monolayers up to 87 monolayers have been also studied. The light-hole exciton is found to be more sensitive to the growth direction than the heavy-hole one.