Birefringence-Directed Raman Selection Rules in 2D Black Phosphorus Crystals

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• 作者：Nannan Mao ; Juanxia Wu ; Bowen Han ; Jingjing Lin ; Lianming Tong and Jin Zhang
• 刊名：Small
• 出版年：2016
• 出版时间：May 18, 2016
• 年：2016
• 卷：12
• 期：19
• 页码：2627-2633
• 全文大小：1424K
• ISSN：1613-6829

文摘

The incident and scattered light engaged in the Raman scattering process of low symmetry crystals always suffer from the birefringence-induced depolarization. Therefore, for anisotropic crystals, the classical Raman selection rules should be corrected by taking the birefringence effect into consideration. The appearance of the 2D anisotropic materials provides an excellent platform to explore the birefringence-directed Raman selection rules, due to its controllable thickness at the nanoscale that greatly simplifies the situation comparing with bulk materials. Herein, a theoretical and experimental investigation on the birefringence-directed Raman selection rules in the anisotropic black phosphorus (BP) crystals is presented. The abnormal angle-dependent polarized Raman scattering of the A_g modes in thin BP crystal, which deviates from the normal Raman selection rules, is successfully interpreted by the theoretical model based on birefringence. It is further confirmed by the examination of different Raman modes using different laser lines and BP samples of different thicknesses.