Magnetophotoluminescence of GaN/AlxGa1-xN quantum wells: Valence band reordering and excitonic binding energies - art. no. 245319

A reordered valence band in GaN/AlxGa1-xN quantum wells with respect to GaN epilayers has been found as a result of the observation of an enhanced g f actor (g*similar to3) in magnetoluminescence spectra in fields up to 55 T. This has been caused by a reversal of the states in the strained AlxGa1-xN barriers thus giving different barker heights for the different quantum wel l hole states. From k-p calculations in the quasicubic approximation, a cha nge in the valence band ordering will account for the observed values for t he g factors. We have also observed the well-width dependence of the in-pla ne extent of the excitonic wave function from which we infer an increase in the exciton binding energy with the reduction of the well width in general agreement with theoretical calculations of Bigenwald et al. [Phys. Status Sokidi B 216, 371 (1999)] that use a variational approach in the envelope f unction formalism that includes the effect of the electric field in the wel ls.