Abstract
A method for designing carbon nanotube field-effect transistors (CNTFETs) with optimized oxide thickness is proposed herein. The optimum oxide thickness that provides the maximum current ratio (on/off ratio) is calculated for each design. The effect of oxide thickness on the on/off ratio is investigated by treating it as the independent variable and calculating the on-state and off-state currents. Particle swarm optimization is used to determine the exact optimum oxide thickness to achieve the maximum current ratio, which is one of the most important parameters in switching applications. The optimum insulator thickness is calculated for CNTFETs with different chiral vectors, insulator types, channel lengths and source/drain doping levels. For further study of the CNTFETs, performance parameters including cutoff frequency and transconductance of the devices are also calculated and investigated. The results show that CNTFET designers should select the oxide thickness very carefully, not simply based on reported values in other works. Each design requires its own optimum oxide thickness which provides the maximum on/off current ratio only for that design.
Highlights
Because of the unique physical and electrical properties of carbon nanotubes (CNTs), they have been paid much attention as electronic material in molecular and nanoscale electronic devices [1,2,3]
The optimum insulator thickness is calculated for Carbon nanotube field-effect transistors (CNTFETs) with different chiral vectors, insulator types, channel lengths and source/drain doping levels
We propose using PSO for tuning the gate insulator thickness with the goal of achieving maximum on/off current ratio
Summary
Because of the unique physical and electrical properties of carbon nanotubes (CNTs), they have been paid much attention as electronic material in molecular and nanoscale electronic devices [1,2,3]. Larger carrier mobility in CNTs caused higher current density and operation frequency of the CNTFETs. Performance optimizations of carbon nanotube FETs have been under study for some years [8,9,10]. 2- Using PSO (particle swarm optimization) algorithm with the ability of finding exact value of the oxide thickness for which the on/off current ratio is maximum. We propose using PSO for tuning the gate insulator thickness with the goal of achieving maximum on/off current ratio. The optimum oxide thicknesses have been calculated for CNTFETs with different CNT chiralities, oxide materials, channel lengths and source/drain doping concentrations.The objective of the optimization is to obtain the maximum current ratio (on/off ratio). The proposed structures have been designed based on the PSO outputs (optimum gate oxide thickness) which provide the maximum possible on/off ratios.
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