Three-Dimensional Transport Simulations and Modeling of Densely Packed CNTFETs

Carbon nanotube (CNT) field-effect transistor (FET) based applications require multiple CNTs with small tube pitches for competing with existing silicon technologies. The associated dense packing of CNTs leads to electrostatic interactions between the tubes also known as screening effects. In this paper, the impact of the latter on the CNT current and charge density has been investigated by means of three-dimensional (3D) device simulation (TCAD), in which the CNT is represented by its actual 3D structure rather than by a one-dimensional (1D) line, allowing to include the effects of an inhomogeneous charge and current density distribution along the CNT circumference. Different analytical models describing the impact of the oxide thickness, CNT diameter and CNT pitch on the oxide capacitance are compared. Using the most accurate model, the dependence of drain current, transconductance, subthreshold slope and transit frequency on the above mentioned parameters has been determined using TCAD simulations.