Growth, Characterization and Comparisons of Few-layer Boron Nitride Nanosheets and Graphene
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Growth, Characterization and Comparisons of Few-layer Boron Nitride Nanosheets and Graphene H. X. Zhang, M. Sajjad and P. X. Feng * Department of Physics and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00931, USA *Corresponding author: Fax: +17877567717. E-mail: [email protected] (P. X. Feng) ABSTRACT Few-layer hexagonal boron nitride (h-BN) nanosheets were produced by using super-short-pulse laser produced plasma deposition techniques. Scanning electron microscopy, Energy dispersive x-ray spectroscopy, and micro-Raman spectroscopy were used to explore the morphologies, elemental concentrations and bond structures of the few-layer h-BN nanosheets. High-quality transparent few-layer h-BN nanosheet with the width up to more than 6 µm, and length more than 20 µm were successfully obtained. The change in contrast suggests that the number of atomic layers varies over the area. A comparative study between the obtained few-layer h-BN nanosheets and the previously synthesized few-layer graphene were also conducted in order to further investigate the properties of the promising 2-Dimention (2D) nanomaterials. Our results suggest that the development h-BN nanosheets has the potential to revolutionize the understanding of 2-D nanomaterials with delocalized electronsheralding a transformative technology with dramatic future implications. INTRODUCTION Boron nitride (BN), in a similar way with carbon, is a synthetic material fashionable in both hexagonal and cubic structures [1,2]. Hexagonal BN (h-BN) consists of sp2-bonded twodimensional layers comprising alternate boron and nitrogen atoms in a honeycomb arrangement; these layers are stacked and van der Waals bonded to form a highly anisotropic threedimensional crystal. The overall structure and atomic spacings of h-BN are very similar to carbon-based graphite [3-5]. In h-BN, however, the boron and nitrogen atoms are alternately stacked directly on top of each other on the adjacent atomic layers resulting in AAA stacking while graphite maintains an offset Bernal structure ABA. In addition, the slightly ionic bonding (both in plane and out of plane) in h-BN further sets this material apart from graphite. h-BN is electrically insulating with a large band gap both within and across the layers while graphite is a semimetal with high levels of conductivity within the layers[6,7]. Since its experimental discovery in 2004, graphene, a single atomic layer of graphite, has brought us a new revolution in materials science due to its many charming, unusual properties [8,9]. For example, graphene is the strongest material ever measured, chemically stable and inert, and conducts electricity better than any other known material at room temperature. These outstanding mechanical, chemical, and electronic properties have stimulated great interest and extensive experimental and theoretical research on the graphene-based materials family. Furthermore, Graphene can even exist as free-standing membrane, thus exposing two surfaces
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