Hunting for Monolayer Boron Nitride: Optical and Raman Signatures

• DOI: 10.1002/smll.201001628
• Publication Date: 2011-01-07T09:11:25Z
• Authors: Roman V. Gorbachev; Ibtsam Riaz; Rahul R. Nair; Rashid Jalil; Liam Britnell; Branson D. Belle; Ernie W. Hill; Kostya S. Novoselov; Kenji Watanabe; Takashi Taniguchi; Andre K. Geim; Peter Blake
• Keywords: optical properties; Boron Compounds; Condensed Matter - Materials Science; Microscopy; Condensed Matter - Mesoscale and Nanoscale Physics; graphene; Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences; 02 engineering and technology; Spectrum Analysis, Raman; Nanostructures; boron nitride; Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Raman spectra; two-dimensional crystals; 0210 nano-technology

We describe the identification of single- and few- layer boron nitride. Its optical contrast is much smaller than that of graphene but even monolayers are discernable by optimizing viewing conditions. Raman spectroscopy can be used to confirm BN monolayers. They exhibit an upshift in the fundamental Raman mode by up to 4 cm-1. The number of layers in thicker crystals can be counted by exploiting an integer-step increase in the Raman intensity and optical contrast.