In this paper, a mid-/long-wave dual-band detector with N-M-π-B-π-N sturcture was developed based on type-II InAs/GaSb superlattice was fabricated by adopting the dual-band structure. The dual-band detector epi-layer presented high crystalline quality of epi-layers. The two channels, with respective 50% cut-off wavelength at 3.5 μm and 11.8 μm were obtained. The peak quantum efficiency (QE) of mid wavelength infrared (MWIR) band and long wavelength infrared (LWIR) band were 22% at 2.7 μm under no bias voltage and 23% at 9.1 μm under -180 mV, respectively. The resistance under 0 and -180 mV of applied bias were 1.7×104 Ω·cm<sup></sup>2 and 97 Ω·cm<sup>2</sup>. Due to the high resistance of long wavelength infrared channel, the specific detectivity of LWIR band maintains above 10<sup>11</sup> cm·Hz<sup>1/2</sup>/W from 4.5 μm to 12.6 μm under - 180 mV at 77K. Finally, the thermal images of both channel were taken by the fabricated FPA.
Since InAs/GaSb type-II superlattices (T2SL) were first proposed as infrared (IR) sensing materials, T2SL
mid-wave IR (MWIR) and long-wave IR (LWIR) are of great importance for a variety of civil and military applications.
A very important parameter of IR photodetectors is dark current, which affects the detectivity directly. Chemical and
physical passivation has revealed to be an efficient technique to reduce surface component of dark current, which will
become a dominant current in focal plane arrays (FPA). In this paper we talk about the electrochemistry and dielectric
method for passivation. We choose anodic sulfide and SiO<sub>2</sub> passivation. The leakage current as a function of bias voltage
(I–V) results show dark current of anodic sulfide device was two orders of magnitude lower than unpassivation one, but
reactive magnetron sputtering SiO<sub>2</sub> didn’t perform well. The highest R<sub>0</sub>A we get from the sulfurizing experiment is
657Ω·cm<sup>2 </sup>in 77K. After fabrication the measured cutoff wavelength is 5.0μm. Finally blackbody test result shows that
the peak quantum efficiency (QE) at 3.33μm is 68% and the peak detectivity is 7.16x10<sup>11</sup>cm·Hz<sup>1/2</sup>/W.