SENSITIVE IR BOLOMETERS USING SUPERCONDUCTING YBACUO AIR BRIDGES ON MICROMACHINED SILICON SUBSTRATES

We have fabricated freestanding epitaxial YBaCuO microbolometers by si licon micromachining. These superconducting devices have their resisti ve transition above 86 K, so they operate at temperatures around 88 K, at the maximum of the slope of the resistance versus temperature char acteristic. Photoresponse measurements and simulation are used to opti mize the geometry and the thermal coupling of the microstructures. Due to their low thermal conductance and mass, which determine the high s ensitivity and speed, they should outperform any existing detectors op erated at or above 77 K at wavelengths longer than 20 mu m.