Fabrication of Bi-La-Sr-Mn-O uncooled microbolometer

Since perovskite manganese oxide Bi-La-Sr-Mn-O (BLSMO) has a large temperature coefficient of resistance (TCR: defined as 1/R dR/dT) of above 3%/K, it has been considered to be a suitable candidate for use as an uncooled IR bolometer material. We fabricated a single pixel device of the BLSMO microbolometer and evaluated it. The BLSMO film was deposited by RF magnetron sputtering at ambient temperature in an oxygen atmosphere. The film showed the TCR of 3.1%/K at room temperature. The size of the single pixel device is 38 × 38 μm². To achieve high infrared absorption, the detector contains an infrared absorbing membrane with a high fill factor of 90%. In a vacuum, the detector showed a thermal conductance of 1.3 × 10^-7 W/K and a responsivity of 4.8 × 10⁵ V/W. According to these numerical values, a noise equivalent temperature difference (NETD) of the BLSMO microbolometer was estimated as being about 0.1 K with f/1.0 optics.