Dimension effect on the performance of carbon nanotube nanobolometers

Carbon nanotube (CNT) film nanobolometers take advantages of high infrared absorption of CNTs, proving a promising alternative for low-cost, uncooled infrared detection. The performance of the CNT nanobolometers is determined by the optoelectronic process on CNTs at a microscopic scale, which links intimately to the diameter of the CNT-a critical parameter that intrinsically affects the band gap and hence infrared absorption, as well as extrinsically affects the surface oxygen adsorption effect and thermal-link of the CNT detector element to the environment. Both the intrinsic and extrinsic factors play important roles in the photoresponse, noise spectrum and the figure-of-merit detectivity D* of the CNT nanobolometers and their interplay determines the device's ultimate performance. In this work, we present a systematic study of the effect of CNT diameter in the range of 1-50 nm on the physical properties relevant to CNT nanobolometers. The optimal CNT diameter was found to be in the range of 2-12 nm with the D* up to 3.3 x 10(7) cm(Hz)W-1/2(-1), which represents an order of magnitude improvement over the best D* reported previously on CNT film nanobolometers.