Microbolometers with a large negative temperature coefficient have been fabricated using an epitaxial GaAs layer grown at low temperature (LTGaAs). The detector elements used have potential in composite bolometer structures where high dR/dT materials can be used without having to be impedance matched to the antenna structure. The LTGaAs material exhibited a thermally activated conduction mechanism (Ea ~ 0.3 eV) with temperature coefficients of -0.05 K-1 and -0.02 K-1 at 110 K and 290 K respectively. Thermal impedance calculations suggest that the negative temperature coefficient produces filamentary electrical paths. Intrinsic dc detector responsivities as high as 108 V/W have been extracted from I-V measurements.
Jason M. Lewis, Jason M. Lewis,
"Low growth temperature GaAs microbolometers", Proc. SPIE 1514, 15th International Conference on Infrared and Millimeter Waves, 15143B (1 December 1990); doi: 10.1117/12.2301529; https://doi.org/10.1117/12.2301529