Photoluminescence and modulation spectroscopy study of the effects of growth interruptions on the interfaces of GaAsSb/GaAs multiple quantum wells

摘要

Temperature dependent photoluminescence (PL), room temperature phototransmittance (PT), contactless electroreflectance (CER) and wavelength modulated surface photovoltage spectroscopy (WMSPS) measurements are utilized to study the effects of growth interruption times, combined with Sb exposure of GaAsSb/GaAs multiple quantum wells (MQWs) structures. The PL spectra show peak location red-shifted, luminescence intensity increased and full width at half maximum narrowed with increasing interruption time. The features originated from different regions of the samples including interband transitions of MQWs, interfaces and GaAs are observed and identified through a detailed comparison of the obtained spectra and theoretical calculation. The anomalous temperature dependence of PL spectra has been attributed to the carrier localization effect resulted from the presence of Sb clusters and/or fluctuations in Sb composition at the QW interfaces. An additional feature has also been observed below the GaAs region in Sb exposure treated samples and the probable origin of this feature has been discussed.