Annealing effects in InGaAsSb quantum wells with pentenary AlInGaAsSb barriers

Abstract

We have previously shown that rapid thermal annealing (RTA) of Te-doped GaSb can increase the n-type carrier concentration (Bugge et al 2004 13th Int. Conf. on Mol. Beam Epitaxy (Edinburgh)). In order to see whether this process can be used on a complete laser structure, we have studied the effect of RTA on the active layers and cladding layers of a GaSb-based laser, as well as on the defect structure in the material. Multiple-quantum-well (MQW) structures of InGaAsSb/AlGaAsSb and InGaAsSb/AlInGaAsSb were grown by molecular beam epitaxy (MBE) on GaSb substrates. The MQW structures were examined with photoluminescence (PL) and x-ray diffraction prior to and after RTA at 625°C and at 650°C for 10 s to look for differences in the (QW) structure. Highly Te-doped layers of GaSb grown by MBE were examined with PL to yield some information on the change in defect structure during RTA. The results show that atomic interdiffusion across the QW heterointerfaces plays a major role during RTA and that it can reduce interface strain for InGaAsSb/AlInGaAsSb MQWs. The diffusion length of group-III atoms was found to be about 2 nm after annealing at 650°C for 10 s.