Exciton binding energies in GaN/AlGaN quantum-well structures

We calculate the exciton binding energies in GaN/AlxGa1-xN quantum wells using a variational technique in momentum space and an effective-mass theory, where the hole kinetic energy is described by a Rashba-Sheka-Pikus Hamiltonian. We investigate the effects of well width and Al molar fraction in the barrier region, including the valence band hybridization and the strain effect in the heterojunctions. Using the effective-mass parameters determined from the cubic approximation for the wurtzite structure, the calculated exciton peak energies are found to be in good agreement with available experimental data. In optical absorption spectra, we find several forbidden transitions which are attributed to the valence band mixing.