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

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 (pi layer) are composed by 8 ML/8 ML and 12.5 ML/7 ML InAs/GaSb superlattices. The cutoff wavelength is 4.8 mu m under forward bias called MWIR channel and expands to 10 mu m under reverse bias called LWIR channels. The responsivities are 0.27 A/W at 4.2 mu m at forward 300 mV bias, while 0.31 A/W at 9 mu m 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 x10(-5) A/cm(2) and 4.51 x10(-2) A/cm(2) for two channels under different bias. The peak detectivity of MWIR diode is calculated to 2 mu 0 x 10(12) cm center dot Hz(1/2)/W at 4.2 mu m and 1.0 x 10(10) cm center dot Hz(1/2)/W at 9 mu m for LWIR channel.