Intermixed quantum well photodetectors for long wavelength detection

Intermixing of the well and barrier layers in quantum well infrared photodetectors (QWIPs) can be used to realize a broadened spectral response as well as multiple color detectors. We describe the experimental results of bom rapid thermal annealing (RTA) and laser annealing (LA) QWIPs operating in the 8-12μm regime. The peak spectral response of the annealed detectors was shifted to longer wavelength as compared to the as-grown detectors. In general, a decrease in detector performance after annealing is also observed which may be attributable to a change in the absorption coefficient caused by the out-diffusion of dopants during annealing. Recent advances in growth technology, complimented by innovative structures should offset any degradation in performance. Thus, the post-growth control of the composition profiles by annealing offers opportunities to fine tune various aspects of a QWIP's response.