Terahertz sensing with carbon nanotube layers coated on silica fibers: Carrier transport versus nanoantenna effects

Carbon nanotube layers prepared as coatings on silica fibers are found to be suitable for terahertz detection in 0.5-7.3 THz range within temperatures of 4.2-70 K. In time-domain of terahertz excitation, two following constituents in the photoresponse are discriminated: the first one is attributed to the bolometric effect while the other one is related to the photoconductivity caused by the terahertz-induced hopping effect. In frequency domain, nonmonotonic behavior of the photoconductivity is associated with prevailing carbon nanotube-induced antenna effects in the electronic transport. The experimental observations are supported by theoretical estimates. (C) 2010 American Institute of Physics. [doi:10.1063/1.3478009]