High performance bias-selectable dual-band Short-/Mid-wavelength Infrared Photodetectors based on Type-Ⅱ InAs/GaSb/AlSb superlattices

摘要

Active and passive imaging in a single camera based on the combination of short-wavelength and mid-wavelength infrared detection is highly needed in a number of tracking and reconnaissance missions. Due to its versatility in band-gap engineering, Type-Ⅱ InAs/GaSb/AlSb superlattice has emerged as a candidate highly suitable for this multi-spectral detection. In this paper, we report the demonstration of high performance bias-selectable dual-band short-/mid-wavelength infrared photodetectors based on InAs/GaSb/AlSb type-Ⅱ superlattice with designed cut-off wavelengths of 2μm and 4μm. Taking advantages of the high performance short-wavelength and mid-wavelength single color photodetectors, back-to-back p-i-n-n-i-p photodiode structures were grown on GaSb substrate by molecular beam epitaxy. At 150 K, the short-wave channel exhibited a quantum efficiency of 55%, a dark current density of 1.0×10~(-9) A/cm~2 at -50 mV bias voltage, providing an associated shot noise detectivity of 3.0×10~(13) Jones. The mid-wavelength channel exhibited a quantum efficiency of 33% and a dark current density of 2.6×10~(-5) A/cm~2at 300 mV bias voltage, resulting in a detectivity of 4.0×10~(11)Jones. The operations of the two absorber channels are selectable by changing the polarity of applied bias voltage.