Here we investigated the effect of post-growth rapid thermal annealing (RTA) on dot-in-a-well infrared photodetectors. In a photoluminescence (PL) study, we initially observed a small red shift in the ground-state PL peak upon annealing to 650 C but then saw the usual blue shift as the annealing temperature increased. We also observed increases in the dark current as the annealing temperature increased up to 700 C but a sudden decrease in the dark current at 750 C. Activation energy is calculated using temperature-dependent PL and dark current measurements. The photoresponse peak was observed at 6.41 μm for the as-grown device. As we increased the annealing temperature to 800 C, the peak response shifted to 9.52 μm. Thus, we achieved wavelength tunability of peak photoresponse using the post-growth annealing technique. © 2013 Elsevier Ltd. All rights reserved.