Attainment of high sensitivity at elevated operating temperatures with staring hybrid HgCdTe-on-sapphire focal plane arrays

Abstract

Cost-effective high-performance IR imaging cameras need affordable staring focal plane arrays (FPAs) that can operate effectively at temperatures compatible with inexpensive long-life coolers. We report on staring hybrid 128 x 128 and 256 x 256 Hg_1-<i>x</i>Cd_<i>x</i>Te FPAs that have requisite yield, sensitivity, operability, and reliability at a medium-wavelength IR (MWIR) cutoff wavelength (λ_<i>c</i> ~4.6 μm at 180 K) and elevated operating temperatures. Mean 256 x 256 FPA noise-equivalent temperature differences (NEΔT) using broadband <i>f</i>/1.7 optics were 4.3, 7.7, and 55 mK at 120, 140, and 180 K, respectively. We extrapolate that camera NEΔT ≤ 0.02 K can be achieved at 190 K using optimized (λ_<i>c</i> of ~4.4 μm (180 K), a 3.4- to 4.2-μm bandpass filter, and <i>f</i>/1 optics. Because the CMOS multiplexers have a low-power dissipation and need little ancillary circuitry in the dewar, a viable thermoelectrically-cooled FPA technology is thus implied once the λ_<i>c</i> is optimized for MWIR imaging.