The January 10, 2014, issue of the journal Science features a report on a promising collaboration by researchers from the University of Tennessee College of Engineering (COE), the Center for Nanophase Materials Science (CNMS) at Oak Ridge National Laboratory (ORNL), and Sandia National Laboratory.
The paper, titled “Heteroepitaxial Growth of Two-Dimensional Hexagonal Boron Nitride Templated by Graphene Edges,” details a new technique for forming a two-dimensional, single-atom sheet of two different materials with a seamless boundary. The study could enable the use of new types of two-dimensional hybrid materials in technological applications and fundamental research.
A UT team, including Gong Gu, an associate professor in the Department of Electrical Engineering and Computer Science; Lei Liu, a post-doctoral researcher; and Wan Deng, a graduate research assistant, co-authored the paper with ORNL’s Jewook Park, Kendal Clark, Juan Carlos Idrobo, Leonardo Basile and An-Ping Li; and Sandia’s David Siegel and Kevin McCarty.
The researchers combined two materials—graphene and hexagonal boron nitride—into a single layer only one atom thick. Graphene has attracted attention as a “wonder material” because of its high strength and electronic properties. To expand the uses of graphene for applications and devices, it needs to be integrated with other materials.
One method to combine differing materials into heterostructures is epitaxy, in which one material is grown on top of another in three-dimensional space so that both have the same crystalline structure. To grow the two-dimensional materials, the research team directed the growth process horizontally instead of vertically. The researchers first grew graphene on a copper foil, etched the graphene to create clean edges, and then grew boron nitride through chemical vapor deposition.
Instead of conforming to the structure of the copper base layer as in conventional epitaxy, the boron nitride atoms took on the crystallography of the graphene. The researchers dubbed the growth “heteroepitaxy in two-dimensional space.”
The research teams used advanced characterization techniques—ORNL’s scanning tunneling microscopy and spectroscopy, and scanning transmission electron microscopy; and Sandia’s low energy electron microscopy and diffraction—to fully prove the epitaxial structure on both atomic and mesoscopic scales.
The new technique will allow researchers to experimentally investigate the scientifically intriguing graphene-boron nitride boundary for the first time.
Read the study here.
Read more from ORNL here.
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