High concentration bolometric system with single-walled carbon nanotubes (SWCNT) absorber

Abstract

We demonstrate that a planar single-walled carbon nanotube (SWCNT) film bolometer can exhibit enhanced thermal and optical properties. The SWCNT film were ink-printed on an oxidized silicon substrate between two pointed-tip Au electrodes across a gap of approximately 10 μm. We obtained a bolometer figure-of-merit temperature coefficient of resistance (TCR) of greater than –3.0%/K at room temperature. An optical response of 1000 V/W was obtained from a 786 nm laser with an output power of 5 mW. The corresponding thermal time constant of 1.8 ms was estimated through the optical response by modulating the laser over a frequency range of 1 Hz to 1 kHz. The optical noise equivalent power (NEP) and optical detectivity of 4.5×10^-11 W/Hz^1/2 and 4.9×10⁸ cmHz^1/2/W, respectively, were estimated from the responsivity, the spectral density, and area of the cell of the absorber, 4.9x10^-4 cm². We attribute the exceptional performance of the SWCNT microbolometer to the film nature of the absorber and to the high concentration of the incident electromagnetic radiation and localized heating between the tips of the electrode.