Single-wall carbon nanotube coating on a pyroelectric detector

Carbon single-wall nanotubes (SWNTs) are studied as the thermal-absorption coating on a large area pyroelectric detector. The SWNTs were produced by a laser vaporization method and dispersed onto the detector surface by use of a simple airbrush technique. The detector was based on a 1-cm-diameter, 60-microm-thick lithium tantalate disk having nickel electrodes. We report the spectral responsivity of the detector ranging from 600 to 1800 nm, as well as the spatial and directional uniformity at 850 nm. Using Drude and Lorentzian dielectric functions and an effective medium approximation to obtain the indices of refraction of semiconductor and metallic SWNTs, we compared the expected theoretical relative responsivity for the two types of tube with the measured relative responsivity of the detector. Values of thermal conductivity, specific heat, and damage threshold obtained from the literature are compared with properties of alternatives for thermal coatings such as gold-black and carbon-based paint.