InAs/GaSb Superlattice-Based Photodiodes with pπMn Structure for Bias-Selectable Mid/Long Wave Dual-Color Infrared Response

Abstract

We demonstrate the bias-selectable mid- or long-wave infrared detectors composed by back-to-back pin-nip diodes with “M” barrier inserted in two diodes to suppress the dark current. Mid-wave infrared (MWIR) and long-wave infrared (LWIR) active region (π layer) are composed by 8 ML/8 ML and 12.5 ML/7 ML InAs/GaSb superlattices. The cutoff wavelength is 4.8 μm under forward bias called MWIR channel and expands to 10 μm under reverse bias called LWIR channels. The responsivities are 0.27 A/W at 4.2 μm at forward 300 mV bias, while 0.31 A/W at 9 μm at reverse 400 mV bias at 77 K. The dependence of the response on the bias is due to the competition of the built-in electric field from the two junctions. The current–voltage curve and the quantum efficiency were measured at 77 K. The dark current densities are 22.7×10−5 A/cm2 and 4.51×10−2 A/cm2 for two channels under different bias. The peak detectivity of MWIR diode is calculated to 2.0×1012 cm·Hz1/2/W at 4.2 μm and 1.0×1010 cm·Hz1/2/W at 9 μm for LWIR channel.