Comparison of the reflectivity spectra of GaAs-AlGaAs coupled and uncoupled asymmetric double quantum wells

Abstract

Comparison between the low temperature reflectivity spectra of GaAs-Al_0.3Ga_0.7As coupled and uncoupled asymmetric double quantum wells with nominal well widths of 90Ã… and 51Ã…  and nominal barrier widths of 25Ã… and 150Ã… is presented. For both the coupled and uncoupled quantum wells, higher order energy transitions were observed in the reflectivity spectra. Qualitative information on the carrier lifetime between wells was obtained based on the oscillator strength and relative broadening of the reflectivity features. Furthermore, possible occurrence of spatially indirect energy transitions due to wavefunction coupling between wells was observed associated with coupling effects both in the conduction and valence bands.