Fabrication and Characterization of Self Assembled Molecular Monolayers Based Electronic Devices

Abstract

Efficient, miniaturized, lightweight, and cost-effective electronic devices are the need of the moment. The main goal of electronic researchers is to increase the performance of FETs, which are the building blocks of microelectronics, but the issue of trade-off between mobility and ION/IOFF is still prevalent in currently used FETs, which decreases its performance. To overcome this, SWCNTs were used as an active region, and Self Assembled Monolayer (SAM) was used as a gate dielectric. Three different SAMs of differing dielectric constant (Octanethiol (OT), Dodecanethiol (DDT), Benzyl Mercaptan (BMT)) were employed as a gate dielectric in SWCNT-FET. Two different concentrations of SWCNTs were used. SAMs were grown by immersion method while SWCNTs were deposited by the drop-casting method. After the preparation of SWCNT-FET, various analyses were performed using different characterization tools. Electrical measurements were done by Keithley source meter. It was observed that CNTFETs with low concentrations had ten times better properties as compared to high concentration ones. Among SAMs, DDT with low concentration showed an optimum balance between ION/IOFF ratio and mobility. Raman and FTIR spectroscopy was used to confirm the successful deposition of SWCNTs and SAMs in fabricated devices. Analysis of CNTFETs showed that they performed very well considering SAMs as the only gate dielectric. Devices performance can be further improved by taking pure semiconducting CNTs as a channel, and passivation of channel surface with SAMs to avoid oxidation and contamination from the environment.