Optical Properties of Boron Nitride and Graphene Nanoribbons: A Time Dependent Density Functional Theory Simulation

The boron nitride (BN) sheet [1], just the analogue of graphene, has attracted wide attention due to its useful properties such as a complementary 2D dielectric substrate for graphene electronics. The BN nanoribbons (BNNRs), which were recently produced under unwrapping multiwalled BN nanotubes, show semiconducting properties due to edge states and imperfections, and have width-dependent energy-band gaps [2] that can be tuned by transverse electric fields. Thus, the BN nanostructures can be promising materials in opto-electronics as functional semiconductors. In the present study we report the results of dielectric properties of the BN nanostructures with the comparison of their carbon analogues by the real-time time-dependent density functional theory in the linear response regime to calculate the dielectric function [3]. Our results have reproduced plasmon peaks in electron energy loss spectra (EELS) of h-BN and the BN sheet observed in a very recent experiment [4]. The profiles of EELS spectra become more similar to those of absorption spectra for BN structures with lower dimension, especially for BNNRs, indicating that the electronic excitations of low dimensional BN structures occur mostly through particle-hole excitations. The detailed comparisons of the results with their carbon analogues and also with the results calculated by the independentparticle approximation will be given in the presentation. [1] H. Zeng, C. Zhi, Z. Zhang, X. Wei, X. Wang, W. Guo, Y. Bando, and D. Golberg, Nano Lett. 10, 5049 (2010). [2] C. Hu, R. Ogura, N. Onoda, S. Konabe, and K. Watanabe, Phys. Rev. B 85, 245420 (2012). [3] G. F. Bertsch, J.-I. Iwata, A. Rubio, and K. Yabana, Phys. Rev. B 62, 7998 (2000). [4] C. T. Pan, R. R. Nair, U. Bangert, Q. Ramasse, R. Jalil, R. Zan, C. R. Seabourne, and A. J. Scott, Phys. Rev. B 85 , 045440 (2012). APPC12 The 12th Asia Pacific Physics Conference