Temperature dependence of photoluminescence from single core-shell GaAs–AlGaAs nanowires

Temperature-dependent polarized microphotoluminescence measurements of single $\mathrm{Ga}\mathrm{As}∕\mathrm{Al}\mathrm{Ga}\mathrm{As}$ core-shell nanowires are used to probe their electronic states. The low-temperature emission from these wires is strongly enhanced compared with that observed in bare GaAs nanowires and is strongly polarized, reflecting the dielectric mismatch between the nanowire and the surrounding air. The temperature-dependent band gap of the nanowires is seen to be somewhat different from that observed in bulk GaAs, and the PL rapidly quenches above $120\mathrm{K}$ , with an activation energy of $17\mathrm{meV}$ reflecting the presence of nonradiative defects.