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.