Thermal escape of carriers out of GaAs/AlxGa1−xAs quantum-well structures

Nonradiative recombination processes in thin GaAs/${\mathrm{Al}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum-well (QW) and double-barrier quantum-well structures have been investigated by means of continuous-wave and time-resolved photoluminescence (PL) measurements. We find that, due to the temperature dependence of the radiative time constant, the Arrhenius plot of the PL intensity cannot be used for extracting the activation energy of the nonradiative channels. In fact it is the temperature dependence of the PL decay time ${\mathit{T}}_{\mathit{L}}$ which directly gives information on the thermal activation of the loss mechanism. The activation energies obtained from the Arrhenius plot of ${\mathit{T}}_{\mathit{L}}$ demonstrate that, at least in the case of thin wells, the main nonradiative mechanism is the thermal escape of the less-confined species of carriers.