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HL: Fachverband Halbleiterphysik

HL 98: Graphene: Spintronics, transistors, and sensors (with DY/MA/O/TT)

HL 98.1: 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).