Investigation of the emissivity and suitability of a carbon thin film for terahertz absorbers

Abstract

The main goal of this work is to optimize the emissivity of terahertz (THz) thermal sensors by deposition of a carbon thin film. Previously, these thermal sensors were designed to detect THz radiation utilizing metamaterials in a complicated optical probing scheme. We have repurposed them to absorb terahertz radiation, convert the radiation to heat, and convey that surface temperature as an infrared image, essentially mapping the terahertz domain. This design has the potential to be used for optical applications such as an attachable lens that would convert any IR (infrared) camera into a THz camera. Additionally, by using this technique, we show that carbon thin films produce sufficient spectral emissivity for IR-based readout. We ascertained that to deposit a carbon thin film an iron catalyst is needed; pure aluminum cannot be used as a catalyst for chemical vapor deposition (CVD) of carbon. Overall, this study provides a viable method to fabricate thin carbon films at low temperatures for IR-based readout.