Plasma-treated carbon nanotubes for fast infrared bolometers

Abstract

Carbon nanotube films are a promising class of materials for bolometric photodetectors due to a unique combination of extremely thin (nm-sized) free-standing form factor with small thermal capacity and intriguing electronic and optical properties, thereby, ensuring high sensitivity and high speed of operation. Nevertheless, the key parameter for bolometric sensor material—the temperature coefficient of resistance (TCR)—is unacceptably low limiting the application of the carbon nanotube films. Here, we examine the plasma treatment of single-walled carbon nanotube (SWCNT) films as the effective method for the TCR enhancement. We study the effect of different plasma gases (oxygen, nitrogen, and hydrogen) on the conductivity of treated films. Also, we investigate the effect of defectiveness, length, and bundling degree of the SWCNTs on TCR. The optimized procedure allows to increase the TCR up to 1.7% K−1 by modulus at 100 K and to 0.8% K−1 at 300 K. The bolometer prototypes based on the plasma-treated SWCNT films demonstrate high sensitivity over a wide IR range (∼21 V/W), a short response time (∼1 ms), and low noise equivalent power (∼8 × 10−9 W Hz−1/2) at the temperature of 100 K.