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!
Atomic structure of ultrasound material not what anyone expected
21.02.2018 | North Carolina State University
Hidden talents: Converting heat into electricity with pencil and paper
20.02.2018 | Helmholtz-Zentrum Berlin für Materialien und Energie
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
21.02.2018 | Materials Sciences
21.02.2018 | Health and Medicine
21.02.2018 | Physics and Astronomy