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Seamless Staircase Electrical Contact to Semiconducting Graphene Nanoribbons
Nano Letters ( IF 9.6 ) Pub Date : 2017-09-08 00:00:00 , DOI: 10.1021/acs.nanolett.7b02938
Chuanxu Ma 1 , Liangbo Liang 1 , Zhongcan Xiao 2 , Alexander A. Puretzky 1 , Kunlun Hong 1 , Wenchang Lu 1, 2 , Vincent Meunier 3 , J. Bernholc 1, 2 , An-Ping Li 1
Affiliation  

Electrical 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.

中文翻译:

与半导体石墨烯纳米带的无缝楼梯电接触

与低尺寸(low-D)材料的电接触是其电子应用的关键。与低D半导体的传统金属接触通常会产生能锁定费米能级(E F)的间隙状态。但是,低D金属在E F处具有有限的态密度可以实现门可调功功能和接触壁垒。而且,与界面处的天然键的无缝接触而没有局部界面状态可以用作最佳电极。为了实现这种无缝接触,需要从原子开始发展原子精确的异质结。在这里,我们演示了与超窄扶手椅石墨烯纳米带(aGNRs)的全碳阶梯接触。宽度可变的aGNR的相干异质结构由7个,14个,21个以及最多56个碳原子组成,通过单分子前体的表面辅助自组装过程合成。在拉曼光谱中,aGNR表现出特征性的振动模式。结合扫描隧道显微镜和密度泛函理论研究揭示了界面的天然共价键性质和准金属接触特性。我们对这种无缝GNR阶梯进行的电子测量构成了制造低电阻触点的有希望的第一步。
更新日期:2017-09-08
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