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.