Fabrication of Electronic Devices Based on Near Percolation Nanotube Networks

Abstract

Electronic gadgets that are efficient, compact, light, and cost-effective are in high demand. The fundamental objective of the researchers is to improve the performance of FETs, which are the building blocks of microelectronics. However, the trade-off between mobility and ION/IOFF remains a problem in today's FETs, lowering their performance. The Problems such as the instability of gate dielectric to withstand high threshold voltage in currently used CNTFETs are still unresolved. Also, single CNT based transistors are hard to realize for commercial used due to complexity of the fabrication method. To overcome these problems, firstly, self-assembled Monolayers (SAMs) can be used as a gate dielectric. Secondly to achieve single path CNT active region, lowest possible area coverage of carbon nanotubes much closer to percolation nanotube networks can be used. 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 different dielectric constants (Octanedithiol (ODT), Dodecanethiol (DDT), Cyclohexanethiol (CHT)) 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. The effective deposition of SWCNTs and SAMs in fabricated devices was confirmed by Raman and FTIR spectroscopy. When CNTFETs were analyzed with SAMs as the only gate dielectric, they performed exceptionally well. Using pure semiconducting CNTs as a channel and passivating the channel surface with SAMs to prevent oxidation and contamination from the environment can boost the device's performance even further.