Optical transitions and type-II band lineup of MBE-grown GaNAs/GaAs single-quantum-well structures

We have investigated transitions above and below band edge of GaNAs/GaAs an d InGaNAs/GaAs single quantum wells (QWs) by photoluminescence (PL) as well as by absorption spectra via photovoltaic effects. The interband PL peak i s observed to be dominant under high excitation intensity and at low temper ature. The broad luminescence band below band edge due to the nitrogen-rela ted potential fluctuations can be effectively suppressed by increasing indi um incorporation into InGaNAs. In contrast to InGaNAs/GaAs QWs, the measure d interband transition energy of GaNAs/GaAs QWs can be well fitted to the t heoretical calculations if a type-II band lineup is assumed. (C) 2001 Elsev ier Science B.V. All rights reserved.