Two-dimensional focal plane detector arrays for LWIR/VLWIR space and airborne sounding missions

Abstract

An increasing need for high-precision atmospheric data especially in the long wavelength infrared (LWIR) and very long wavelength infrared (VLWIR) spectral ranges has arisen in the past years not only for the analysis of climate change and its effect on the earth's ecosystem, but also for weather forecast and atmospheric monitoring purposes.Spatially and spectrally resolved atmospheric emission data are advantageously gathered through limb or nadir sounding using an imaging Fourier transform (FT) interferometer with a two-dimensional (2D) high-speed focal plane detector array (FPA).In this paper, AIM reports on its latest results on MCT VLWIR FPAs for Fourier transform infrared sounding applications in the 8-15µm spectral range. The performance of a (112x112) pixel photodiode array with a 40µm pixel pitch incorporating extrinsic p-doping for low dark current, a technique for linearity improvement at high photon fluxes, pixel guards, pixel select/de-select, and a (2x2) super-pixel architecture is discussed. The customized read-out integrated circuit (ROIC) supporting integrate while-read (IWR) operation has a buffered direct injection (BDI) input stage and a full well capacity (FWC) of 143 Megaelectrons per super-pixel. It consists of two independently operating halves with two analog video outputs each. The full frame rate is typically 4k frames/sec, making it suitable for use with rapid scan FT infrared spectrometers.At a 55K operating temperature and an ∼14.4µm cut-off wavelength, a photo response of 12.1mV/K and a noise equivalent temperature difference of 24.8mK at half well filling are demonstrated for a 286K reference scene. The nonlinearity error is <0.5%.

Below Rule’07 low dark current LWIR and VLWIR MCT 2D focal plane detector arrays from AIM

“…Notably, the measured dark current figure implies that the devices may be operated at an about 20K higher operating temperature for the same dark current level than extrinsically doped AIM n-on-p LWIR and VLWIR MCT FPAs from the previous technology generation [3,4,5] (dashed blue line in the figure). 8.…”

“…With LWIR HOT detector applications more and more evolving, AIM as a leader in LWIR MCT detectors has addressed the challenge. We like to note that AIM has a long standing track record on dark-current reduction, especially by extrinsic Au doping in the LWIR and VLWIR spectral range [3,4,5,6]. During the last couple of years we matured our p-on-n LWIR technology, a key technology for high-performance small pixel pitch planar LWIR HOT MCT devices [9].…”

Very long wave infrared quantum cascade detectors

“…The very long wave infrared (VLWIR, λ ＞ 14μm) is a strategic band for the development of space-based infrared technology, such as atmospheric temperature profiling, pollution monitoring, infrared astronomy and satellite mapping [1][2][3] . However, the infrared detectors are often limited to high dark current and low work temperature in view of the wake signal in this range.…”