Abstract
In this study, we demonstrate 12×12µm2 high-performance, dual-band, long-wavelength infrared (LWIR) photodetectors based on InAs/GaSb/AlSb type-II superlattices. The structure consists of two back-to-back heterojunction photodiodes with 2µm-thick p-doped absorption regions. High quality dry etching combined with SiO2 passivation results in a surface resistivity value of 7.9×105Ωcm for the longer (red) channel and little degradation of the electrical performance. The device reaches dark current density values of 4.5×10−4A/cm2 for the longer (red) and 1.3×10−4A/cm2 for the shorter (blue) LWIR channels at quantum efficiency saturation. It has 50% cut-off wavelengths of 8.3 and 11.2µm for the blue and red channel, respectively, at 77K in back-side illumination configuration and exhibits quantum efficiencies of 37% and 29%, respectively. This results in specific detectivity values of 2.5×1011cm·Hz1/2/W and 1.3×1011cm·Hz1/2/W at 77K.
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