Effect of growth temperature and post-growth thermal annealing on carrier localization and deep level emissions in GaNAs/GaAs quantum well structures

We report results from investigation of the optical properties of GaNAs/GaAs quantum well structures. The structures were grown by molecular-beam epitaxy at different temperatures, and subsequently postgrowth thermal treatments at different temperature were performed. The results show that the carrier localization is smaller in a structure grown at a temperature of 580 °C in comparison with a structure grown at 450 °C. Both structures also show a broaden deep level emission band. Furthermore, the deep level emission band and the carrier localization effect can be removed by thermal annealing at 650 °C in the structure grown at 450 °C. The structure quality and radiative recombination efficiency are significantly improved after annealing. However, annealing under the same condition has a negligible effect on the structure grown at 580 °C.