2005/08/18 by Ludger Wirtz, Wirtz, Ludger, Andrea Marini +7 · 1 citation
Engineering · Materials Science · Physics and Astronomy · #Boron and Carbon Nanomaterials Research #Diamond and Carbon-based Materials Research #Nanowire Synthesis and Applications #cond-mat.mtrl-sci
paper · pdf · doi:10.48550/arxiv.cond-mat/0508421
5 pages, 5 figures
arxiv created 2005/08/18 · arxiv updated 2009/12/01
A new interpretation of the optical and energy-loss spectra of hexagonal boron nitride is provided based on first-principle calculations. We show that both spectra cannot be explained by independent-particle transitions but are strongly dominated by excitonic effects. The lowest direct and indirect gaps are much larger than previously reported. The direct gap amounts to 6.8 eV. The first absorption peak at 6.1 eV is due to an exciton with a binding energy of 0.7 eV. We show that this strongly bound Frenkel exciton is also responsible for the low frequency shoulder of the pi plasmon in the energy-loss function. Implications for nanotube studies are discussed.