High detectivity uncooled thermal detectors with resonant cavity coupled absorption in the long-wave infrared

We describe uncooled thermal detectors with a peak detectivity of at least 3 × 10⁹ cm √Hz/W with spectrally selective absorption in the long-wave infrared. The spectral selectivity in absorption is achieved through resonant cavity coupling of a thin metal film with a low-order air-gap optical cavity. The electrical readout uses thermoelectric thin films with a Johnson noise limited performance. The detectors are of multiple sizes but those with 100-μm² area have time constants of 58 ms and thermal conductances of 2.3 × 10^-7 W/K.