Mid-wavelength focal plane arrays infrared detector based on type-II InAs/GaSb superlattice

A mid-wavelength $$128 \times 128$$ infrared focal plane arrays based on InAs/GaSb type-II superlattice was presented in this work. Superlattice materials were grown on GaSb substrates using MBE technology, which was confirmed by XRD, TEM and AFM analyses. Absorber structure for mid-wavelength detector was designed to be 8 ML InAs/8 ML GaSb. The pixel of the detector had a conventional PIN structure with a size of $$50\,\upmu \hbox {m}\times 50\,\upmu \hbox {m}$$ . The device fabrication process consisted of mesa etching, side-wall passivation, metallization, and flip-chip hybridization with readout integrated circuit, epoxy backfill, lap, and polish. The dark current I–V curve was measured from 77 K up to 297 K. The responsivity spectra, photoluminescence peak wavelength and blackbody current responsivity were measured at 77 K. The detector had a cut-off wavelength of $$4.8\,\upmu \hbox {m}$$ , photoluminescence peak wavelength of $$4.4\,\upmu \hbox {m}$$ , peak detectivity of $$7.1\times 10^{11}\,\hbox {cm}\,\hbox {Hz}^{1/2}\,\hbox {W}^{-1}$$ , quantum efficiency of 50 %. The PIN diode may reach a typical value of $$\hbox {R}_{0}\hbox {A}$$ of $$5.0\times 10^{5}\Omega \,\hbox {cm}^{2}$$ . Pixel operability of the detector was more than 98 %, the non-uniformity was 4.3 %, and the mean NETD value was lower than 20 mK. Concept proof of infrared imaging was also demonstrated with the focal plane array at 77 K.