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

Abstract

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.