Anomalous temperature and excitation power dependence of cathodoluminescence from InAs quantum dots

Self-assembled InAs quantum dots (QDs) in GaAs layers were studied with a cathodoluminescense (CL) detection system combined with a transmission electron microscope. Three distinct peaks were observed to appear in the CL spectrum collected from a 1?m2 region. The excitation power dependence of the CL spectra and monochromatic CL image observations identified those peaks that are the emissions associated with the ground state and excited state of the QDs in different size groups. Anomalous temperature dependence of those QD emission peaks was observed in the temperature range from 20 to around 100 K, where the emission intensities increase with temperature. Steady-state rate equations for the recombination processes of holes and excitons are proposed with introduction of a potential barrier at the interface between the GaAs layer and the wetting layer (WL). This model can explain the temperature dependence of the emission intensities from the QDs and WL in a wide temperature range.