Correlation between the light- and heavy-hole free-exciton fine structure in AlxGa1-xAs-GaAs multiple-quantum-well structures using photoluminescence excitation spectroscopy.

Abstract

Sharp line structure associated with both the light-hole free exciton (LHFE) and heavy-hole free exciton (HHFE) in multiple-quantum-well structures of GaAs-${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As in photoluminescence and reflection spectra has been deconvoluted by using photoluminescence excitation spectroscopy. A correlation is established between particular LHFE fine-structure components and specific HHFE fine-structure components. A model is developed to account for the LHFE and HHFE fine structure in these samples which exploits the nonrandom character of the observed spectra. The physical location of the excitons is demonstrated to be in regions of the well(s) with essentially identical interfacial microstructure. Evidence of diffusion from effectively-narrow-well regions to wide-well regions is presented.