Line-shape analysis of reflectance spectra from coupled, weakly coupled, and uncoupled GaAs-AlGaAs asymmetric double quantum wells
Reflectance measurements were used in conjunction with photoluminescence measurements to probe the higher order energy transitions in GaAs-AlGaAs asymmetric double quantum wells. Reflectance spectra were fitted with a Lorentzian dielectric model that incorporated the effect of multilayer interference. Difficulties in the fitting of the higher order resonances of the narrow well are attributable to the degeneracy of such resonances with the heavy-hole continuum. Fit parameters yielded greater oscillator strengths and smaller damping parameters for the wide well transitions as compared to those of the narrow well due to narrow well to wide well carrier tunneling when significant coupling is present between wells. Such results indicate higher transition probabilities and longer state lifetimes for wide well transitions compared to narrow well transitions as the coupling between wells is increased.