N-composition and pressure dependence of the inter band transitions of Ga(N,As)/GaAs quantum wells

A series of GaNxAs1-x/GaAs quantum well structures with well widths of about 20 nm and x varying between 1% and 3.5% has been grown by metal-organic vapour phase epitaxy. We have studied the evolution of the quantum well states under hydrostatic pressure up to 20 kbar at 300 K by photomodulated reflectance (PR) spectroscopy. The energy positions of the quantum well transitions have been obtained by fitting the PR spectra. The pressure dependence of the allowed heavy-hole transitions enhhn decreases with increasing n. This directly reflects the strong non-parabolic dispersion of the conduction band originating from the interaction of the N-impurity level with the bands of the GaAs host. The fitted energy positions and their pressure dependence can be well described by a 10 band k.p model. The observed splitting between the lowest light-hole and heavy-hole transitions are in agreement with a type I band alignment.