Influence of substrate and biasing current on response of YBCO microbolometers

The authors fabricated YBCO thin films by RF magnetron sputter deposition onto ZrO/sub 2/, SrTiO/sub 3/, LaAlO/sub 3/, and MgO substrates and patterned these films into microbolometers. The influence of substrate type and device biasing current on the response of the microbolometers was measured. The responsivity and the speed of the devices were found to depend on the thermal conductivity of the substrates used. The fastest YBCO device was found on MgO, whereas the largest bolometric response was found on ZrO/sub 2/. It was found that the responsivity of a microbolometer increased with biasing current, but there was an optimal biasing current beyond which device performance deteriorated due to self heating. The results indicate that the most sensitive microbolometer requires a sharp YBCO resistivity transition, a low thermal conductivity substrate, and an optimal biasing current.>