YBaCuO uncooled microbolometer IRFPA

Because the semiconducting YBaCuO films which are fabricated by sputtering have a temperature coefficient of resistance (TCR) over 3 %/K at room temperature, they are considered to be candidates for bolometer materials of uncooled infrared (IR) detectors. There is a problem, however, in that the resistivity of the films is over 10 Ohmcm, which is two orders of magnitude higher than that of conventional VOX bolometer films. To decrease the resistance of the bolometers, we researched sputtering conditions of the YBaCuO films and combined them with comb-shaped electrodes. When the YBaCuO film was deposited on these electrodes by RF magnetron sputtering at room temperature in an atmosphere of 2% 02 and 98% Ar, it showed a resistivity of 90 Ohmcm and a TCR of -3.2%/K; ultimately the YBaCuO bolometer resistance became 82 kOhm using the comb-shaped electrodes. The YBaCuO bolometer detector that contains an infrared absorbing membrane achieved a high fill factor of 90% and high infrared absorptance of 79%. Moreover, the detector showed a thermal conductance of 1.3 X 10(-7) W/K and a responsivity of 6.8 X 10(5) V/W in a vacuum. The YBaCuO microbolometer FPA which we have developed has an array format of 320 X 240 pixels and a pixel pitch of 40 mum. The FPA showed a noise equivalent temperature difference (NETD) of 0.08 K with a prototype camera and f/1.0 optics.