Temperature-dependent luminescence of GaAs doping superlattices

The photon energy of the luminescence between spatial separated n- and p-type doped layers of GaAs doping superlattices shifts with excitation density. At room temperature we observe a shift of the luminescence maximum in samples with high doping concentrations (n=4×10¹⁸cm⁻³), whereas for n=1×10¹⁸cm⁻³ this shift is observed at temperatures below 150K only. Temperature-dependent measurements between 4 and 700K show that the tunability disappears near a critical temperature, which is proportional to the doping concentration. A simple model including thermally activated direct transitions and tunable luminescence describes this temperature dependence.