IR characterization of carbon-black for thermopile infrared detectors

In this paper, the p-poly-Si/Al thermopile infrared detector, with a single layer of low-stress SiN_x membrane, instead of previous designed thin sandwich layer membrane of SiO₂-Si₃N₄ is presented. Meanwhile, we investigate the influence of carbon-black coating on the output response of the detector. Infrared (IR) transmission spectra measurements made on absorbing area of the detector with carbon-black and without carbon-black reveal that IR absorbance to different wavelengths is enhanced distinctly, especially from 1μm to 8μm, when carbon-black is evaporated on the surface of the detector. Based on the IR transmission spectra and the output voltage measurements, the response sensitivity and the specific detecitivity of the detector without carbon-black are 12.45V/W, 4.64×10⁷ cmHz^(1/2) W^-1, respectively; while the response sensitivity and the specific detecitivity of the detector with carbon-black are 13.30 V/W, 4.96×10⁷ cmHz^(1/2) W^-1. The output response of the detector increases by 6.9%, when carbon-black is applied to the surface of the absorbing area of the detector.