Enhancing the Luminescence Efficiency of GaSb-Based Dilute-Nitrides by Rapid Thermal Annealing

It has been shown that gallium antimonide (GaSb)-based dilute-nitrides display improved photoluminescence (PL) with in situ annealing in the molecular beam epitaxy (MBE) growth chamber under a Sb ambient. This improvement in luminescence efficiency translates into improved performance of optoelectronic devices, such as lasers, where this will lead to a reduction in threshold current densities. However, similar improvement in luminescence efficiency was not observed during ex situ annealing in a rapid thermal annealing (RTA) furnace. The ability to recreate similar annealing performance in the RTA would allow for increasingly efficient annealing. Upon further study, we determined that the degradation in PL resulted from over-annealing of the sample. Attributing this issue to the silicon (Si) carrier wafer, which has a higher band gap than the GaSb sample, infrared radiation was heating the sample more than indicated by the carrier wafer pyrometer measurement. We mitigated this issue by integrating a low bandgap indium arsenide (InAs) layer into the carrier wafer and were able to ensure that our sample was below the temperature indicated by the pyrometer. This optimization allowed us to pinpoint the optimal annealing temperature more accurately and achieve PL performance similar to that of in situ annealing.