Tfets

INVITED PAPER

Graphene for CMOS and Beyond CMOS Applications

The unique properties of graphene, which consists of a few layers of carbon atoms, are discussed in this paper.

By Sanjay K. Banerjee, Fellow IEEE , Leonard Franklin Register, Emanuel Tutuc, Member IEEE , Dipanjan Basu, Seyoung Kim, Dharmendar Reddy, and Allan H. MacDonald

ABSTRACT

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Owing in part to complementary metal–oxide–

I . INTRODUCTION

Since its first discovery in 2004 [1], graphene has been studied intensively thanks to its unique electron physics, as well as for promising applications to electronic devices. Graphene’s high intrinsic carrier mobility (over 200 000 cm2 /Vs at low temperature for levitated samples [2]), $400-nm mean free path, and Fermi velocities of 1/300 the speed of light (108 cm/s) which are 10Â that in Si can in principle lead to high on-state field-effect transistor (FET) currents. This, combined with its true 2-D nature, makes graphene channels the ultimate ultrathin body metal–oxide–semiconductor fieldeffect transistor (MOSFET), which is attractive from an electrostatic gate control point of view. But unfortunately graphene is also a gapless semiconductor, which leads to high off-state leakage and nonsaturating drive currents which are problematic for digital logic. Graphene also has a unique linear bandstructure, unlike the parabolic EðkÞ relation in most semiconductors, leading to what are known as Dirac massless Fermions, which can lead to so-called perfect Klein tunneling though barriers, making graphene FETs (GFETs) harder to shut off. Nevertheless, the unique bandstructure, transport properties, and thermodynamic stability make it a very promising material for high-frequency FET and beyond complementary metal–oxide–semiconductor (CMOS) nanoelectronic devices [1], [3]. Graphene has attracted attention as a high-mobility channel replacement for Si in MOSFETs for highfrequency applications. For example, GFETs are potentially useful for low noise...