Analytical device model for graphene bilayer field-effect transistors using weak nonlocality approximation

Abstract

We develop an analytical device model for graphene bilayer field-effect transistors (GBL-FETs) with the back and top gates. The model is based on the Boltzmann equation for the electron transport and the Poisson equation in the weak nonlocality approximation for the potential in the GBL-FET channel. The potential distributions in the GBL-FET channel are found analytically. The source-drain current in GBL-FETs and their transconductance are expressed in terms of the geometrical parameters and applied voltages by analytical formulas in the most important limiting cases. These formulas explicitly account for the short-gate effect and the effect of drain-induced barrier lowering. The parameters characterizing the strength of these effects are derived. It is shown that the GBL-FET transconductance exhibits a pronounced maximum as a function of the top-gate voltage swing. The interplay of the short-gate effect and the electron collisions results in a nonmonotonic dependence of the transconductance on the top-gate length.

Application of Carbon Nanotubes(CNT) on The Computer Science and Electrical Engineering:A Review

“…Graphene transistors, like CNTFET, can have a variety of back gates and combined gates (upper and lower) [131,132]. Single-layer graphene field effect transistors with an energy band gap of zero and two-layer ones with finite energy band gap have been theoretically studied and their characteristics have been reported by many studies [133][134][135][136][137][138][139][140][141]. With a honeycomb structure of an atomic layer width, graphene was mechanically separated from graphite for the first time in late 2004 [142].…”

Non-Quasi-Static Effects in Graphene Field-Effect Transistors Under High-Frequency Operation

“…The design of highfrequency (HF) circuits using these emergent devices requires an appropriate description of its behavior. Many GFET models have been proposed comprising large-signal and small-signal varieties [3][4][5][6][7][8][9][10][11][12][13][14][15][16] but all of them based on a quasi-static (QS) approximation, where the fluctuation of the varying terminal voltages is assumed to be slow, so the stored charge in the device could follow the voltage variations. Such an approximation is found to be valid when the transition time for the voltage to change is less than the transit time of the carriers from source to drain.…”

Advances in graphene-based optoelectronics, plasmonics and photonics

“…Subsequently, the first observation of current saturation in zero-bandgap, top-gated graphene field-effect transistors was reported by Shephard et al [3], and Rogers [4] discussed the synthesis of ultrathin films of reduced graphene oxide with large area and their possible utilization in flexible electronics and other applications. Ryzhii et al investigated the tunneling currentvoltage characteristics of graphene and graphene nanoribbon field-effect transistors [5,6], the device model for graphene bilayer field-effect transistors [7], high-frequency properties of graphene nanoribbon field-effect transistors [8] and an analytical device model for graphene bilayer field-effect transistors, using a weak nonlocality approximation [9]. In reference [10] Duan et al demonstrated the fabrication of high-speed graphene transistors with a self-aligned nanowire Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.…”