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Seamless Staircase Electrical Contact to Semiconducting Graphene Nanoribbons
journal contribution
posted on 2017-09-06, 00:00 authored by Chuanxu Ma, Liangbo Liang, Zhongcan Xiao, Alexander A. Puretzky, Kunlun Hong, Wenchang Lu, Vincent Meunier, J. Bernholc, An-Ping LiElectrical
contact to low-dimensional (low-D) materials is a key
to their electronic applications. Traditional metal contacts to low-D
semiconductors typically create gap states that can pin the Fermi
level (EF). However, low-D metals possessing
a limited density of states at EF can
enable gate-tunable work functions and contact barriers. Moreover,
a seamless contact with native bonds at the interface, without localized
interfacial states, can serve as an optimal electrode. To realize
such a seamless contact, one needs to develop atomically precise heterojunctions
from the atom up. Here, we demonstrate an all-carbon staircase contact
to ultranarrow armchair graphene nanoribbons (aGNRs). The coherent
heterostructures of width-variable aGNRs, consisting of 7, 14, 21,
and up to 56 carbon atoms across the width, are synthesized by a surface-assisted
self-assembly process with a single molecular precursor. The aGNRs
exhibit characteristic vibrational modes in Raman spectroscopy. A
combined scanning tunneling microscopy and density functional theory
study reveals the native covalent-bond nature and quasi-metallic contact
characteristics of the interfaces. Our electronic measurements of
such seamless GNR staircase constitute a promising first step toward
making low resistance contacts.
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gate-tunable work functionsSemiconducting Graphene Nanoribbons Electrical contactlow-Dultranarrow armchair graphene nanoribbonssurface-assisted self-assembly processquasi-metallic contact characteristicsGNRall-carbon staircase contactaGNRscanning tunneling microscopyE FSeamless Staircase Electrical ContactTraditional metal contacts56 carbon atoms
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