Semiconducting YBCO bolometers for uncooled IR detection

Amorphous semiconducting Y-Ba-Cu-O is attractive as the temperature sensitive element for uncooled LR bolometers and pyroelectric detectors. Thin films can be easily fabricated by RF magnetron sputtering at room temperature from a composite target. It is compatible with micromachining techniques for the fabrication of thermally isolated structures. As a bolometer, Y-Ba-Cu-O possesses a relatively high temperature coefficient of resistance of 3.5% K-1 near room temperature. This paper will present the IR characteristics of 40-mum x 40-mum microbolometer arrays fabricated in thermal isolation structures. These detectors are aimed at thermal imaging at 10-mum wavelength. Recently, self-supporting YBaCuO pixels have been developed. In this case, the Y-Ba-Cu-O thin film pixel requires no underlying bridge material to provide structural support. The Y-Ba-Cu-O thin film is supported solely by the electrode arms. Responsivity and detectivity greater than 4x10(3) V/W and 10(8) cmHz(1/2)/W respectively have been measured in these detectors. The development of large area 1.5-mm and 0.4-mm square YBaCuO bolometers for NASA's global warming studies in low-orbiting satellites will also be presented. These large area detectors require large optical bandwidths covering the 0.3-mum to 100-mum wavelength band.