Exclusion principle and screening of excitons in GaN/AlxGa1-xN quantum wells - art. no. 035315

We model the variation of the exciton binding energy and of the oscillator strength versus temperature in strained GaN/AlxGa1-xN quantum wells by usin g a self-consistent variational procedure. In addition, this method is exte nded to the case of high photoinjection conditions. We thus can properly ac count for the effect of a dense electron-hole plasma on the excitonic wave function, and we can quantitatively address the exciton bleaching phenomeno n via quantum exclusion effects. A surprising behavior has been found: the robustness of the exciton to screening by the dense plasma increases with i ncreasing temperature. In other words, the pumping intensity necessary to t ear apart electrons and holes increases with increasing temperature. This i s quantitatively interpreted in terms of the quantum exclusion effect as a straightforward result of the Pauli principle and of the fundamental prescr iptions of quantum mechanics. The limitations imposed by this effect on the excitonic wave functions are relaxed with increasing temperature.