Observation of long-lived oblique excitons in GaN-AlGaN multiple quantum wells

The 2-K recombination dynamics of coupled GaN-AlGaN multiple quantum wells reveals a composite nature in terms of the joint contributions of short-liv ed direct excitons and long-lived oblique ones. The possibility to observe these oblique excitons, which produce a unusual blueshift of the photolumin escence at long decay times is found to be in straightforward correlation w ith the presence of internal electric fields together with the existence of a slight disorder at the monolayer scale. [S0163-1829(99)09815-X].