title: High-speed graphene transistors with a self-aligned nanowire gate.
abstract: Graphene has attracted considerable interest as a potential new electronic material. With its high carrier mobility, graphene is of particular interest for ultrahigh-speed radio-frequency electronics. However, conventional device fabrication processes cannot readily be applied to produce high-speed graphene transistors because they often introduce significant defects into the monolayer of carbon lattices and severely degrade the device performance. Here we report an approach to the fabrication of high-speed graphene transistors with a self-aligned nanowire gate to prevent such degradation. A Co(2)Si-Al(2)O(3) core-shell nanowire is used as the gate, with the source and drain electrodes defined through a self-alignment process and the channel length defined by the nanowire diameter. The physical assembly of the nanowire gate preserves the high carrier mobility in graphene, and the self-alignment process ensures that the edges of the source, drain and gate electrodes are automatically and precisely positioned so that no overlapping or significant gaps exist between these electrodes, thus minimizing access resistance. It therefore allows for transistor performance not previously possible. Graphene transistors with a channel length as low as 140 nm have been fabricated with the highest scaled on-current (3.32 mA μm(-1)) and transconductance (1.27 mS μm(-1)) reported so far. Significantly, on-chip microwave measurements demonstrate that the self-aligned devices have a high intrinsic cut-off (transit) frequency of f(T) = 100-300 GHz, with the extrinsic f(T) (in the range of a few gigahertz) largely limited by parasitic pad capacitance. The reported intrinsic f(T) of the graphene transistors is comparable to that of the very best high-electron-mobility transistors with similar gate lengths.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Liao
authors.forename: Yung-Chen
authors.initials: YC
authors.lastname: Lin
authors.forename: Mingqiang
authors.initials: M
authors.lastname: Bao
authors.forename: Rui
authors.initials: R
authors.lastname: Cheng
authors.forename: Jingwei
authors.initials: J
authors.lastname: Bai
authors.forename: Yuan
authors.initials: Y
authors.lastname: Liu
authors.forename: Yongquan
authors.initials: Y
authors.lastname: Qu
authors.forename: Kang L
authors.initials: KL
authors.lastname: Wang
authors.forename: Yu
authors.initials: Y
authors.lastname: Huang
authors.forename: Xiangfeng
authors.initials: X
authors.lastname: Duan
mesh_terms: D002138:Calibration; D002244:Carbon / Q000737:chemistry*; D025802:Electric Capacitance; D004566:Electrodes; D004581:Electronics / Q000295:instrumentation*; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure; D013696:Temperature; D014173:Transistors, Electronic
chemical_list: D002244:Carbon
references.citation: ACS Nano. 2009 May 26;3(5):1145-50
references.pmid: 19388670
references.citation: J Am Chem Soc. 2008 Jul 2;130(26):8152-3
references.pmid: 18529002
references.citation: Science. 2006 May 26;312(5777):1191-6
references.pmid: 16614173
references.citation: Nat Nanotechnol. 2007 Oct;2(10):605-15
references.pmid: 18654384
references.citation: Nat Nanotechnol. 2008 Nov;3(11):654-9
references.pmid: 18989330
references.citation: Science. 2010 Feb 5;327(5966):662
references.pmid: 20133565
references.citation: Proc Natl Acad Sci U S A. 2010 Apr 13;107(15):6711-5
references.pmid: 20308584
references.citation: Science. 2007 Sep 14;317(5844):1530-3
references.pmid: 17872440
references.citation: Nat Mater. 2007 Mar;6(3):183-91
references.pmid: 17330084
references.citation: Nat Nanotechnol. 2010 Jul;5(7):487-96
references.pmid: 20512128
references.citation: Nano Lett. 2009 Jan;9(1):422-6
references.pmid: 19099364
references.citation: Science. 2004 Oct 22;306(5696):666-9
references.pmid: 15499015
references.citation: Nano Lett. 2009 Dec;9(12):4474-8
references.pmid: 19883119
references.citation: Nano Lett. 2005 Feb;5(2):287-90
references.pmid: 15794612
references.citation: Adv Mater. 2010 May 4;22(17):1941-5
references.pmid: 20526997
references.citation: Nano Lett. 2010 May 12;10(5):1917-21
references.pmid: 20380441
references.citation: Nature. 2005 Nov 10;438(7065):201-4
references.pmid: 16281031
references.citation: Nature. 2005 Nov 10;438(7065):197-200
references.pmid: 16281030
references.citation: ACS Nano. 2008 May;2(5):1033-9
references.pmid: 19206501