Gate Electrostatics and Quantum Capacitance of Graphene Nanoribbons

TL;DR

This paper investigates the electrostatic and quantum capacitance properties of graphene nanoribbons using atomistic simulations, revealing edge-dependent effects, quantum capacitance differences, and magnetic field influences on C-V characteristics.

Contribution

It provides a detailed analysis of how edge shapes influence the electrostatic and quantum capacitance of GNRs, highlighting differences between zigzag and armchair edges and the impact of magnetic fields.

Findings

Zigzag GNRs have lower gate capacitance due to edge states.

Quantum capacitance of armchair GNRs is half that of zigzag nanotubes.

Magnetic fields cause oscillations in C-V characteristics.

Abstract

Capacitance-voltage (C-V) characteristics are important for understanding fundamental electronic structures and device applications of nanomaterials. The C-V characteristics of graphene nanoribbons (GNRs) are examined using self-consistent atomistic simulations. The results indicate strong dependence of the GNR C-V characteristics on the edge shape. For zigzag edge GNRs, highly non-uniform charge distribution in the transverse direction due to edge states lowers the gate capacitance considerably, and the self-consistent electrostatic potential significantly alters the band structure and carrier velocity. For an armchair edge GNR, the quantum capacitance is a factor of 2 smaller than its corresponding zigzag carbon nanotube, and a multiple gate geometry is less beneficial for transistor applications. Magnetic field results in pronounced oscillations on C-V characteristics.