Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 78: Graphene: Spintronics, Transistors, and Sensors (HL jointly with DY, MA, O, TT)
O 78.1: Vortrag
Donnerstag, 3. April 2014, 15:00–15:15, POT 081
Graphene's RF Potential: How harmful is the Zero Bandgap? — Kyle D. Holland1, Navid Paydavosi1, Neophytos Neophytou2, •Diego Kienle3, and Mani Vaidyanathan1 — 1Department of Electical and Computer Engineering, University of Alberta — 2Institute for Microelectronics, Technical University of Vienna — 3Institute of Theoretical Physics I, University of Bayreuth
With the aid of self-consistent quantum-mechanical simulations and simple expressions for the radio-frequency (RF) metrics, we examine the impact of a lack of a bandgap on limiting the RF potential of graphene transistors. Considering various RF figures of merit, we show that the lack of a bandgap leads to all RF metrics being optimal when the bias point is chosen such that the drain Fermi level aligns with the Dirac point at the midpoint of the channel. We further quantify the precise extent to which the lack of a bandgap limits the transistor's cutoff frequencies, an issue that has been flagged as requiring crucial attention to make graphene transistors competitive. For an 18-nm channel length, we show that the extrinsic unity-current-gain frequency could be improved by 300 GHz and the unity-power-gain frequency could be doubled if a bandgap could be introduced to reduce the output conductance to zero. [1] K. D. Holland, N. Paydavosi, N. Neophytou, D. Kienle, and M. Vaidyanathan, IEEE Trans. Nanotechnol. 12, 566 (2013).