Electron and hole confinement in GaInN/GaN and AlGaN/GaN quantum wells

We show that the strong bowing of the bandgap of GaInN, which is primarily due to bowing of the valence band edge, translates into a strongly composition dependent ratio of the conduction band offset to the valence band offset with respect to GaN. For common In mole fractions of 0-20% this leads to a reversal of the band offset ratio and to very weak electron confinement. This theoretical picture is verified by comparing results of time-resolved spectroscopy on asymmetric AlGaN/GaInN/GaN and AlGaN/GaN/AlGaN quantum wells. Since electron confinement is much stronger for GaN/AlGaN wells than for GaInN/GaN wells, the effect of asymmetry is very weak for the former and fairly strong for the latter.