Towards Multi-Scale Modeling of Carbon Nanotube Transistors

TL;DR

This paper develops multiscale simulation methods for carbon nanotube transistors, focusing on quantum transport modeling using NEGF at atomistic and semi-empirical levels, to better understand their behavior.

Contribution

It introduces a comprehensive multiscale simulation framework for CNTFETs, combining atomistic and semi-empirical approaches for quantum transport analysis.

Findings

Quantum transport effects are accurately described in nanotube transistors.

The semi-empirical and atomistic models are effective for device-level simulations.

The methods can be integrated into broader multiscale modeling hierarchies.

Abstract

Multiscale simulation approaches are needed in order to address scientific and technological questions in the rapidly developing field of carbon nanotube electronics. In this paper, we describe an effort underway to develop a comprehensive capability for multiscale simulation of carbon nanotube electronics. We focus in this paper on one element of that hierarchy, the simulation of ballistic CNTFETs by self-consistently solving the Poisson and Schrodinger equations using the non-equilibrium Greens function (NEGF) formalism. The NEGF transport equation is solved at two levels: i) a semi-empirical atomistic level using the pz orbitals of carbon atoms as the basis, and ii) an atomistic mode space approach, which only treats a few subbands in the tube-circumferential direction while retaining an atomistic grid along the carrier transport direction. Simulation examples show that these approaches describe quantum transport effects in nanotube transistors. The paper concludes with a brief discussion of how these semi-empirical device level simulations can be connected to ab initio, continuum, and circuit level simulations in the multi-scale hierarchy.