Monolithically integrated CdTe/InSb visible/midwave-infrared two-color photodetectors.

Abstract This paper reports on the demonstration of two-terminal, two-color (visible/midwave-infrared, MWIR) photodetectors (2CPDs) consisting of monolithically-integrated CdTe nBn and InSb PN sub-detectors connected by an n-CdTe/p-InSb heterovalent tunnel junction grown on lattice-matched InSb substrates. The 2CPD can be switched between MWIR (1.5–5.5 μm with a peak responsivity of 0.75 A/W at 77 K) and visible (350–780 nm with a peak responsivity of 0.3 A/W) detection bands by applying different optical and electrical biases. Band rejection ratios of 18 dB and 52 dB, and spectral cross-talks of 40 dB and 31 dB are achieved for the visible and the MWIR bands, respectively. This 2CPD can be potentially used for visible/MWIR two-color focal plane arrays with optimal fill-factors and zero spatial offset between the visible and MWIR imaging channels. [ABSTRACT FROM AUTHOR]