Long wavelength infrared detection based on Mn-Co-Ni-O thin films with dielectric-metal-dielectric absorptive structures

We reported the design and performance of a long wavelength infrared thermal sensitive detector based on the Mn_1.56Co_0.96Ni_0.48O₄ (MCNO) thin films. By using a NiCr absorption layer of some ten nanometers, we designed a quarter wavelength resonant cavity together with a Si₃N₄ anti-reflection layer, which improves the absorption in the infrared transparent window of 8–14 μm. We calculated and analyzed the infrared absorption spectra at the atmospheric window, and the results showed that the non substrate absorption increases from less than 25% to 40–70% after coating with dielectric-metal-dielectric absorption layers. The blackbody responsivity enhanced by 2.1 times after the construction of the absorption films, which is about 0.84–1.68 × 10⁷ cm⋅Hz^0.5/W@10 Hz and close to the performance of the detector coated with black paints. The study contributes to the future development of large scale uncooled infrared MCNO thin film detection arrays.