Temperature dependence of the photoluminescence properties and band gap energy of InxGa1-xAs/GaAs quantum wells

The effective band gap energy of InxGa1-xAs/GaAs strained quantum wells (QWs) is investigated by photoluminescence spectroscopy (PL) in the range 12-295 K. The temperature dependence of the band gap energy of strained QWs correlates well with that of bulk InxGa1-xAs of similar composition. Deviations from the band gap variation of bulk material at low temperatures (12-90 K) are interpreted in terms of exciton localization. The differences DELTA E(12 K) between the measured PL peak energies and the expected transition energies at 12 K (obtained by simulating the measured temperature dependence of the PL peak positions by the well-known Varshni relation) are suggested to be closely related to the Stokes shifts that often exist between PL and PL excitation spectra of QWs. A linear relation is found between the PL FWHM measured at 12 K and DELTA E for a range of QWs prepared under different growth conditions. Excitonic recombination is inferred to be dominant in the PL transitions at the highest temperatures investigated, even at RT. 62 refs.