Chemical interconnection bridges electronic properties of graphene-nanoribbons with zigzag-edge features
An international research team at Tohoku University's Advanced Institute of Materials Research (AIMR) succeeded in chemically interconnecting chiral-edge graphene nanoribbons (GNRs) with zigzag-edge features by molecular assembly, and demonstrated electronic connection between GNRs. The GNRs were interconnected exclusively end to end, forming elbow structures, identified as interconnection points (Fig. 1a).
Figure 1 shows interconnected graphene nanoribbons (GNRs). The interconnection points are observed as elbow structures. The inset of (a) shows the chemical structure of an elbow interconnection point of two chiral-edge GNRs. The top panel of (b) shows the scanning tunneling microscopy topograph, highlighting a single GNR and a pair of connected GNRs (elbow). The bottom panel of (b) shows the local density of states (LDOS) of these two structures share the same electronic architecture, including the elbow interconnection point. This indicates that electronic properties, such as electron and thermal conductivities, should be comparable between termini 1-2 and termini 3-4.
Credit: Patrick Han
This configuration enabled researchers to demonstrate that the electronic architecture at the interconnection points between two GNRs (Fig. 1b) is the same as that along single GNRs; evidence that GNR electronic properties, such as electron and thermal conductivities, are directly extended through the elbow structures upon chemical GNR interconnection.
This work shows that future development of high-performance, low-power-consumption electronics based on GNRs is possible.
Graphene has long been expected to revolutionize electronics, provided that it can be cut into atomically precise shapes that are connected to desired electrodes. However, while current bottom-up fabrication methods can control graphene's electronic properties, such as high electron mobility, tailored band gaps and s pin-aligned zigzag edges, the connection aspect of graphene structures has never been directly explored.
For example, whether electrons traveling across the interconnection points of two GNRs would encounter higher electric resistance remains an open question. As the answers to this type of questions are crucial towards the realization of future high-speed, low-power-consumption electronics, we use molecular assembly to address this issue here.
"Current molecular assemblies either produce straight GNRs (i.e., without identifiable interconnection points), or randomly interconnected GNRs," says Dr. Patrick Han, the project leader. "These growth modes have too many intrinsic unknowns for determining whether electrons travel across graphene interconnection points smoothly. The key is to design a molecular assembly that produces GNRs that are systematically interconnected with clearly distinguishable interconnection points."
To reach this goal, the AIMR team used a Cu substrate, whose reactivity confines the GNR growth to six directions, and used scanning tunneling microscopy (STM) to visualize the GNR electronic structures. By controlling the precursor molecular coverage, this molecular assembly connects GNRs from different growth directions systematically end to end, producing elbow structures--identified as interconnection points (Fig. 1a).
Using STM, the AIMR team revealed that the delocalization of the interconnected GNR π*-states extends the same way both across a single straight GNR, and across the interconnection point of two GNRs (periodic features in Fig. 1b, bottom panel). This result indicates that GNR electronic properties, such as electron and thermal conductivities, should be the same at the termini of single GNRs and that of two connected GNRs.
"The major finding of this work is that interconnected GNRs do not show electronic disruption (e.g., electron localization that increases resistance at the interconnection points)," says Han. "The electronically smooth interconnection demonstrates that GNR properties (including tailored band gaps, or even spin-aligned zigzag edges) can be connected to other graphene structures. These results show that finding a way to connect defect-free GNRs to desired electrodes may be the key strategy toward achieving high-performance, low-power-consumption electronics."
About AIMR, Tohoku University
The Advanced Institute for Materials Research (AIMR) at Tohoku University is one of nine World Premier International Research Center Initiative (WPI) Programs established with the support of the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT). The program aims to develop world-class research bases in Japan. After its establishment in 2007, AIMR has been active in conducting research activities and creating new systems in order to become a global center for materials science. Since 2012, AIMR has also been conducting fundamental research by finding connections between materials science and mathematics.
Learn more at http://www.
For information about the research:
Dr. Patrick Han
Advanced Institute for Materials Research, Tohoku University
For information on AIMR and all other enquiries:
Public Relations & Outreach office
Advanced Institute for Materials Research, Tohoku University
Patrick Han | EurekAlert!
Scientists channel graphene to understand filtration and ion transport into cells
11.12.2017 | National Institute of Standards and Technology (NIST)
Successful Mechanical Testing of Nanowires
07.12.2017 | Helmholtz-Zentrum Geesthacht - Zentrum für Material- und Küstenforschung
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
12.12.2017 | Physics and Astronomy
12.12.2017 | Earth Sciences
12.12.2017 | Power and Electrical Engineering