Fabrication and performance of uncooled infrared bolometer based on Mn _1.56Co_0.96Ni_0.48O₄ thin films

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_1.56Co_0.96Ni _0.48O₄ (MCNO) thin films grown on Al₂O ₃ substrate by chemical solution deposition were investigated. The MCNO bolometer sized 300×160 μm² were fabricated by photolithography process followed by wet etching, and the temperature coefficient of resistance reaches -3.81 %K^-1 @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^-21 cm³ 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 ⁷ cmHz^1/2/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.