A first principles theoretical examination of graphene-based field effect transistors

Abstract

This paper presents an in-depth theoretical examination of graphene-based field effect transistors, looking at thermal statistics, electrostatics, and electrodynamics. Using a first principles approach, the unique behavior observed in graphene-based field effect transistors, such as the V-shaped transfer characteristic, limited channel pinch-off, and lack of off-state (under gate modulation), are described. Unlike previous attempts, a description of both drift and diffusion currents in the device is presented. The effect of external resistance on steady-state and high-frequency performance is examined. Comparisons of the theoretical results to experimental results are made and show good agreement. Finally, the theoretical work in this paper is used as a basis to discuss the possible source of some observed behavior in practical graphene-based field effect transistors.

A temperature dependent measurement of the carrier velocity vs. electric field characteristic for as-grown and H-intercalated epitaxial graphene on SiC

“…In order to account for this, the Fermi energy at 300 K is calculated for both materials given the carrier density n sh ðT ¼ 300 KÞ. Assuming a Dirac cone model for the graphene band structure and nondegenerate Fermi-Dirac statistics, the Fermi level may be related to the carrier concentration via the Fermi Dirac integral 18,19 n ¼ N g…”

Development and characterization of graphene-based electronic devices

“…In terms of electrical properties, a first principles physical model has been selected [79] as the starting point. This choice is backed up when considering the amount of variables included in it, such as geometric parameters, dielectric properties, fixed charge sheet density, and, more importantly, electron and hole mobility in graphene.…”

“…Taking into account this distinction between carrier types, a theoretical model exists [79]. In this first principles model, the same parameters available on the previously mentioned methods appear, but carrier mobility for electrons and holes are provided to the calculations separately.…”

“…To obtain this data from GFET assessments, several methods exist, but none of them is capable to distinguish between hole and electron carriers. To solve this, an existing model [79] that overcomes the issue can be fitted into a method adequate to extract the selected figures of merit. This idea has evolved into an electrical characterization suite, programmed in python, where the concepts and equations of the chosen model are included.…”

“…As anticipated, a theoretical model based on first principles [79] has been chosen as the underlying physical framework. This model allows to correlate the GFET transfer characteristics with the electron and hole carrier mobilities, the fixed charge at the surface and the contact resistance.…”