3-WELL ONE-COLOR AND 2-COLOR QUANTUM-WELL INFRARED PHOTODETECTORS

Quantum well infrared photodetectors (QWIP) have been developed rapidl y and large QWIP arrays with 256 x 256 and 640 x 480 elements have bee n demonstrated. But they all use quantum well structures that consist of 30-50 periods which have a relatively small conversion efficiency d ue to the small optical gain. In this paper, a high performance quantu m well infrared photodetector consisting of only three quantum wells i s presented which shows very large conversion efficiencies up to 29% a t a bias voltage -0.8 V and peak wavelength 8.5 mu m. A high strain tw o-stack, two-color QWIP consists of three wells in each stack is also presented here for MWIR and LWIR detection. The MWIR stack has employe d 35% of indium in the InGaAs well which not only achieved peak wavele ngth at 4.3 mu m, but also obtained very high peak responsivity of 0.3 7 A W-1. (C) 1997 Elsevier Science S.A.