Calculation of the Integral Absorption Coefficient of the Sensitive Element of an Uncooled Thermal Detector of the Bolometric Type

Currently, uncooled thermal detectors are among the most popular photodetectors, since they combine acceptable optical characteristics without the need to maintain the desired temperature. The main advantage of uncooled thermal detectors over cooled ones is the relative cheapness of manufacture. This also implies the main disadvantage - a decrease in sensitivity due to the effect of the ambient temperature on the device. Changing the thickness of the structural layers of the active elements of the microbolometric matrix is one of the most easily accessible ways to increase sensitivity. By modeling the absorption spectra and then calculating the integral absorption coefficient in the wavelength range from 8 to 14 μm, it was found that this coefficient increases from 60 to 81 % with a decrease in the thickness of the absorbing NiCr layer from 10 to 4 nm. The results obtained can be used to improve the optical characteristics of manufactured uncooled thermal detectors of the bolometric type.