InSb is a III-V binary semiconductor material with a bandgap wavelength of 5.4 μm at 77 K, well matched to the 3-5 μm MWIR atmospheric transmission window. When configured as a Focal Plane Array (FPA) detector, InSb photodiodes offer a large quantum efficiency, combined with excellent uniformity and high pixel operability. As such, InSb arrays exhibit good scalability and are an excellent choice for large format FPAs at a reasonable cost. The dark current is caused by Generation-Recombination (G-R) centres in the diode depletion region, and this leads to a typical operating temperature of ∼80 K in detectors with a planar implanted p-n junction. Over the last 15 years SCD has developed and manufactured a number of different 2-dimensional planar FPA formats, with pitches in the range of 15-30 μm. In recent years a new epi-InSb technology has been developed at SCD, in which the G-R contribution to the dark current is reduced. This enables InSb detector operation at 95-100 K, with equivalent performance to standard InSb at 80 K. In addition, using a new patented XB nn device architecture in which the G-R current is totally suppressed, epitaxial InAsSb detectors have been developed with a bandgap wavelength of 4.2 μm, which can operate in the 150-170 K range. In this short review of the past two decades, a number of key achievements in SCD's InSb based detector development program are described. These include High Operating Temperature (HOT) epi-InSb FPAs, large format megapixel FPAs with high functionality using a digital Read Out Integrated Circuit (ROIC), and ultra low Size, Weight and Power (SWaP) FPAs based on the HOT XBnn architecture.
Bibliographical noteFunding Information:
We would like to acknowledge support for this work received from the Chief Scientist of the Israeli Ministry of Trade and Industry (MOITAL).
- Focal plane array
- Infrared detector