Novel hybrid carbon materials for nano-electronics
Tan, Chong Wei
Date of Issue2013
School of Electrical and Electronic Engineering
In this report, detailed studies have been performed on carbon thin films obtained via a filtered cathodic vacuum arc (FCVA). The microstructure of carbon thin film can be modified by applying in-situ techniques (such as thermal and ion energy) or ex-situ techniques (such as laser and electrical pulse). The carbon thin films have been characterized and studied in details with Raman, CAFM, TEM, and IV methods. The improvement in electrical conductivity is due to the formation of nano-crystalline graphitic (NCG) carbon thin film, which served as nano-channels for electrical conduction. The two different in-situ methods of obtaining NCG rich films were compared, and it turns out that the IV characteristic are comparable to one another. The preliminary results for the IV characteristic of carbon films with different thickness from 100 nm to 500 nm have been demonstrated. It has been shown that the IV characteristic remains ohmic as the carbon film thickness increases, which will prove to be interesting for future structural devices that require high electrical conductivity. The in-situ Raman, IV, and TEM have been performed during the post annealing process of the amorphous carbon thin film. The behaviour of the changes from amorphous carbon to NCG has been explored and a hypothesis has been proposed to explain the changes occurring during the conversion of the amorphous carbon to NCG carbon. Two ex-situ techniques for the conversion process, namely laser-induced annealing and electrical pulse induced conversion, have been explored. It is found that there is a compromise between the laser energy and the surface roughness. The optimum laser energy is used to obtain NCG samples, which are being analysed by CAFM, TEM, Raman mapping, and IV metal-carbon-metal (MCM) structures. Overall, the electrical resistivity obtained is higher than the samples obtained via in-situ techniques because the laser energy is limited to ensure a smooth carbon sample surface. It is found that electrical pulse via CAFM or MCM structure can be used to induce NCG carbon films. The IV curves of the conversion progress are shown and discussed. Carbon nanowires have been successfully fabricated via the Langmuir Blodgett (LB) method using polystyrene (PS) balls of diameter 450 nm. Through a series of steps, a carbon nanowire of 500 nm in length and approximately 250 nm in diameter has been successfully produced.
DRNTU::Engineering::Electrical and electronic engineering::Nanoelectronics