Electrical characterizations of asymmetric InAs/GaSb superlattice MWIR photodiodes

InAs/GaSb superlattice pin photodiodes, having an asymmetric period design, exhibited cut-off wavelength in the midwave infrared domain (MWIR) at 5 μm at 77 K. Electrical characterizations including dark-current and capacitance–voltage measurements were performed on single detectors in the temperature range (77–300 K). The SL photodiode measurements revealed carrier concentrations of about 6 × 1014 cm−3 at 77 K, dark-current densities J = 4 × 10−8 A/cm2 at 77 K for Vbias = −50 mV and the measured R0A product is higher than 1.5 × 106 Ω cm2 at 77 K. Comparison to classical pin diodes with symmetric period design show that the differential resistance area product is improved by more than one order of magnitude. This result obtained demonstrates the strong influence of the period on the electrical properties of SL MWIR photodiodes.