Electron-hole plasma effect on excitons in GaN/AlxGa1-xN quantum wells

The self-consistent procedure of solving both the Schrodinger and Poisson e quations for electron and hole wave functions has been combined with the va riational calculation of exciton states in strained GaN/AlxGa1-xN quantum w ells. The procedure accounted properly for the free-carrier effects on the excitonic wave function, namely, the exciton bleaching and the quantum excl usion effects. It also allowed us to quantify the dependence of the exciton energy and of the oscillator strength on the optical pumping density. The calculation revealed an interesting interplay between the screening of the polarization fields, which leads to the increase of the electron-hole overl ap, and the screening of the electron-hole interaction, which affects the: exciton Bohr radius. The peculiar nonmonotonic behavior of the exciton bind ing energy as a function of the density of the electron-hole plasma results from these combined effects.