Fabrication and performance of InAs/GaSb type-II superlattices Mid-wavelength infrared detectors

摘要

Infrared photodetectors were widely applied in satellite detection, infrared-guided, infrared early warning and infrared imaging and so on. Currently, InAs/GaSb type-II superlattices (T2SLs) photodetectors have been attracted by their unique band-structure and potential applications. In this paper, the InAs/GaSb T2SLs photodetectors in mid-wavelength infrared (MWIR) spectral range were fabricated with p-i-n structure, and the process parameters were optimized. The multilayer structure was grown on GaSb substrate by Molecular Beam Epitaxy (MBE). The active area of this photodetector was 260μm×260μm, and the sidewall of mesa was protected by SiO_2 layer. The thickness of adsorption layer was 1060 nm. To reserve more incident area and to avoid the damage caused by welding process, the pad of electrodes were designed under the mesa. A annular electrode was designed to shorten the transmission time of carriers to improve the collection efficiently. The cut-off wavelength λc of the detector was 4.2μm@77K, and the dark current density was measured as 1.07×10~(-3) A/cm~2@V_b=-0.1V. The peak of specific blackbody detectivity (D*) was equal to 1.05×10~(10) cmHz~(1/2)/W at zero-bias.