High-temperature excitons in GaAs quantum wells embedded in AlAs/GaAs superlattices

Photoluminescence (PL) spectra of GaAs quantum wells embedded in short-peri od AlAs/GaAs superlattices have been measured at 2 K and at room temperatur e. Two approaches have been applied in order to investigate the mechanisms of radiative recombination in these structures. In the first one, we studie d the excitation density dependence of the PL intensity. In the second appr oach a line-shape analysis of the PL spectra is performed by means of a sta tistical model, which includes both free exciton, and free carrier recombin ations. The fit based on this model reproduces with high accuracy the exper imental spectra and allows to assess the relative contributions of excitons and free carriers to the radiative recombination process. The results of b oth approaches indicate the predominance of free excitons in the radiative recombination at room temperature. (C) 2000 Elsevier Science Ltd. All right s reserved.