Mn-Co-Ni-O bolometer with spinel structure has been extensively studied as a low resistivity and high sensitivity negative temperature coefficient material for decades. In this paper, the fabrication process and the performance of uncooled infrared bolometer based on Mn<sub>1.56</sub>Co<sub>0.96</sub>Ni<sub>0.48</sub>O<sub>4</sub> (MCNO) thin films grown on Al<sub>2</sub>O<sub>3</sub> substrate by chemical solution deposition were investigated. The MCNO bolometer sized 300×160 μm<sup>2</sup> were fabricated by photolithography process followed by wet etching, and the temperature coefficient of resistance reaches -3.81 %K<sup>-1</sup> @296 K. Relatively low excess noise was achieved due to the good quality of fabrication process, and the normalized noise power γ/n was found to be 1.8×10<sup>-21</sup> cm<sup>3</sup> at 296 K. Through black coating the performances for MCNO bolometer, operating at room temperature, are greatly improved and exhibit responsivity of over 354 V/W, detectivity of approximated 4.5×10<sup>7</sup> cmHz<sup>1/2</sup>/W@10Hz at ±16 V, and the thermal time constant of about 18 ms. These experiment results indicate that the infrared detection ability of MCNO thin film bolometer is significantly enhanced comparing with bulk devices.
Mn-Co-Ni-O spinel oxide materials, with the prototype of AB<sub>2</sub>O<sub>4</sub>, are excelled in uncooled thermal sensing and infrared detection due to its high absolute NTC value and moderate resistivity at room temperature. In this work, Mn<sub>1.56</sub>Co<sub>0.96</sub>Ni<sub>0.48</sub>O<sub>4</sub> film (MCN-CSD) and Mn<sub>1.40</sub>Co<sub>1.00</sub>Ni<sub>0.60</sub>O<sub>4</sub> (MCN-RF) film are fabricated on amorphous sapphire substrate with chemical solution method (CSD) and radio frequency deposition method (RF), respectively. Morphological characteristics are revealed by SEM graphs. And the result shows that MCN films acquire better crystalline properties and compactness than MCN bulk materials. To verify the excellent features for infrared detection, detectors sized 1mm<sup>2</sup> × 0.17 μm and 1 mm<sup>2</sup> × 0.33 μm are fabricated based on MCN-RF and MCN-CSD films, respectively. The excess noise at 11 Hz for each detector has been tested and the Hooge's parameters have been calculated. The MCN films obtained by RF deposition and CSD method both show γ/n value of about 2×10<sup>-21</sup> cm<sup>3</sup>, an order lower than bulk MCN and amorphous silicon, which indicates great potentials in integrated infrared detection.