Bias-selectable mid-/long-wave dual band infrared focal plane array based on Type-II InAs/GaSb superlattice

Abstract

In this paper, a mid-/long-wave dual-band detector which combined PπMN structure and unipolar barrier was developed based on type-II InAs/GaSb superlattice. A relevant 320×256 focal plane array (FPA) was fabricated. Unipolar barrier and PπMN structure in our dual band detector structure were used to suppress cross-talk and dark current, respectively. The two channels, with respective 50% cut-off wavelength at 4.5μm and 10μm were obtained. The peak quantum efficiency (QE) of mid wavelength infrared (MWIR) band and long wavelength infrared (LWIR) band are 53% at 3.2μm under no bias voltage and 40% at 6.4μm under bias voltage of −170mV, respectively. And the dark current density under 0 and −170mV of applied bias are 1.076×10−5A/cm2 and 2.16×10−4A/cm2. The specific detectivity of MWIR band and LWIR band are 2.15×1012cm·Hz1/2/W at 3.2μm and 2.31×1010cm·Hz1/2/W at 6.4μm, respectively, at 77K. The specific detectivity of LWIR band maintains above 1010cm·Hz1/2/W at the wavelength range from 4.3μm to 10.2μm under −170mV. The cross-talk, selectivity parameter at 3.0μm, about 0.14 was achieved under bias of −170mV. Finally, the thermal images were taken by the fabricated FPA at 77K.