Thin-film IR absorbers with high absorbance and easy preparation and integration

Thin-film infrared (IR) radiation absorbers are widely used in thermal detectors, and high IR absorption in a wide spectral range is critical to improve the sensitivities of the detectors. In this work, three types of thin-film IR absorbers were prepared and the absorption characteristics were tested. 1 μm thick Styrene Butadiene Styrene block polymer (SBS) decorated multiwall carbon nanotube (MWNT) films, prepared via solution coating, indicate an average absorbance of 92% in the spectral range of 8 ~ 14 μm. 1.5 μm thick nanostructured Cr thin-films, obtained by sputtering at a high incident angle of 110°, reveal an absorbance of 55% at 8 μm which decreases linearly to 35% at 14 μm. 4 μm thick carbonized photoresist thin-films, formed by ion beam etching, imply an absorbance of 83% at 8 μm which declines monotonously to 57% at 14 μm. All the thin-film IR absorbers are easy to fabricate and integrate into thermal detectors without need of specific equipment. The SBS decorated MWNT thin-films show the highest IR absorbance and the best uniformity of spectral response in 8 ~ 14 μm, indicating that they are most suitable to be used as an IR absorber in IR detectors.