Thermally activated carrier escape mechanisms fromInxGa1−xAs/GaAs quantum wells

The temperature dependence of the photoluminescence (PL) intensity of strained ${\mathrm{In}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs single-quantum-well (QW) structures grown by metalorganic vapor-phase epitaxy is investigated. We adopt the theoretical model recently proposed by Vening, Dunstan, and Homewood [Phys. Rev. B 48, 2412 (1993)] to describe the variation of the QW PL intensity with temperature. The Arrhenius behavior of the PL intensity at the highest temperatures investigated for each structure is shown to be due to the thermally activated escape of electron-hole pairs from the well. In each case, the deviation of the experimental data at intermediate temperatures is accounted for by assuming the dominant nonradiative recombination process to be the escape of the less-confined carrier species from the QW. The existing model is modified to include this process. The activation energies obtained are in reasonable agreement with the calculated heavy-hole confinement energies assuming a conduction-band offset ratio of ${\mathit{Q}}_{\mathit{c}}$≊0.83.