Thakur, NK and Eshwar, T and Agarwal, PB
(2019)
Deposition of Uniform SWNTs Thin Film using In-house Developed Spray Coating Set-up.
In: Symposium on Carbon Nanomaterial Electronics(SCNE-2019), November 8-9, 2019, BITS, Pilani, Rajasthan, India.
Abstract
Deposition of carbon nanotubes (CNTs) with uniform distribution over large size substrates is one of the major challenges for the commercialization of based electronics devices/ sensors [1]. Out of the available techniques, ultrasonic spray is a fast and economical method for deposition of CNTs on a variety of substrates [2]. Here we report an in-house developed spray coating set-up and its use to deposit uniform thin film of CNTs over silicon substrates. The setup comprises ultrasonic atomizer probe, motorized X-Y stage, a hot plate for in-situ solvent evaporation, syringe pump for flow control of CNTs suspension, and an exhaust fan (Fig. 1 (a)). The single-walled CNTs (SWNTs) with 0.1 mg/ml suspension in dimethylformamide (DMF) were chosen for spray over silicon dioxide/ silicon (oxide thickness ~ 1 µm) substrates. Keeping distance of 43 mm between substrate to nozzle, and stage speed of 4 mm/s as constants; the flow rate of SWNTs was varied from
1.7 to 2.5 ml/min. The substrate temperature was ~ 160°C for solvent evaporation, and large area was programmed for spray to get uniform film. The sheet resistance mapping of the deposited films was carried out in the centre of the substrates (~ 20 mm X 20 mm area) using four-point probe system. The range of the measured sheet resistance are 2.5-75 kgΩ/o, 1.1-2 kgΩ/o, and 0.9-1.4 kgΩ/o for flow rates of 1.7 (Fig. 1 (b)), 2.1 and 2.5 nil/min (Fig. 1 (c)) respectively. The decreased sheet resistance with increased flow is due to thicker SWNTs film, which would result more number of conductive paths. The developed process would be useful to realize uniform array of SWNTs based devices/ sensors for applications in electronics, biochemical sensors
etc.[3].
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