This paper presents an extended short-wave infrared (eSWIR) image sensor, a large format infrared focal plane array (IRFPA), applied in advanced hyperspectral imager (AHSI) aboard China’s three GaoFen-5 satellites and two more followed ZY-1 satellites. Hyperspectral imaging has been emerged as a very important application in Earth observation instruments, for the spectral detection provides the spectrum information of ground objects except for the spatial imaging of the objects. AHSI has a 60-km swath width and a 30-m spatial resolution, and has high signal-to-noise ratio (SNR) in spectrum of interest. Large format infrared focal plane arrays which are ordinarily used in staring infrared imaging have some special performance requirements when applied in hyperspectral imaging, such as higher quantum efficiency, lower dark current, lower noise and selectable current conversion gain to match the different radiation flux of different subdivided spectral bands. We developed a format of 2048×512 HgCdTe/Si IRFPA sensor (equivalent 2012×256 after pixel overlapping and binning) in which 2012 pixels meet the demands of 60km swath width and 256 pixels line meet the 200 spectral bands. The sensor has 8-level gains selectable by spectral bands, and array dark current densities on an order of 10 ^-10 A/cm ² , quantum efficiency exceeding 80%, and the operability of 99.5% at operating temperature of around 110K. The SNR of this FPA achieved 150 when illuminated under 5×10 ⁴ photons/pixel.

To overcome the limitations of CdZnTe substrates for large-format, low-cost HgCdTe infrared focal plane arrays (IRFPAs), the epitaxial growth of HgCdTe films on alternative substrates (e.g., GaAs and Si) has become an important research focus. The lattice mismatch of approximately 14% between the GaAs alternative substrate and the HgCdTe material generates a high density of interfacial defects, such as dislocations and twins. These defects induce a high density of interface states within the near-interface bandgap, resulting in interfacial recombination and consequently limiting device performance. This paper proposes an optimization method for the HgCdTe/GaAs interface that involves substrate removal and surface passivation after the fabrication of GaAs-based HgCdTe infrared (IR) detectors. The GaAs substrate was removed without damage through chemical mechanical polishing (CMP) and selective wet chemical etching. A bromine-based solution (Br₂–HBr) was employed to eliminate the surface damage layer for interfacial optimization, and a composite dielectric film was deposited to achieve simultaneous surface passivation and optical antireflection. Experimental results on n-on-p devices operating at 80 K demonstrate that after interfacial optimization, the average quantum efficiency across the 3.5–6.1 μm wavelength range increased from 58% to 84% and the blackbody responsivity improved from 8.7 × 10⁶ V/W to 1.6 × 10⁷ V/W. Both quantum efficiency and blackbody responsivity reached levels comparable to those of CdZnTe-based detectors. Numerical fitting based on the carrier diffusion model indicated that interfacial optimization reduced the surface potential by approximately two orders of magnitude, effectively suppressing interfacial recombination.

Thls paper presents a method to improve HgCdTe detectors' performance by anti-reflection coating. Back-illuminated HgCdTe photovoltaic detectors have been fabricated on molecular beam epitaxy (MBE) HgCdTe layer on top of GaAs substrate by ion implantation doping. ZnS film is deposited on the surface of GaAs substrate by magnetron sputtering. With this AR coating, the black body detectivity, responsivity and quantum efficiency have the increase of 41%, 45% and 100% respectively. That is a great help to improve the property of HgCdTe detectors.