Surface-Facet-Dependent Phonon Deformation Potential in Individual Strained Topological Insulator Bi2Se3 Nanoribbons

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• 作者：Yuan Yan ; Xu Zhou ; Han Jin ; Cai-Zhen Li ; Xiaoxing Ke ; Gustaaf Van Tendeloo ; Kaihui Liu ; Dapeng Yu ; Martin Dressel ; Zhi-Min Liao
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：October 27, 2015
• 年：2015
• 卷：9
• 期：10
• 页码：10244-10251
• 全文大小：591K
• ISSN：1936-086X

文摘

Strain is an important method to tune the properties of topological insulators. For example, compressive strain can induce superconductivity in Bi₂Se₃ bulk material. Topological insulator nanostructures are the superior candidates to utilize the unique surface states due to the large surface to volume ratio. Therefore, it is highly desirable to monitor the local strain effects in individual topological insulator nanostructures. Here, we report the systematical micro-Raman spectra of single strained Bi₂Se₃ nanoribbons with different thicknesses and different surface facets, where four optical modes are resolved in both Stokes and anti-Stokes Raman spectral lines. A striking anisotropy of the strain dependence is observed in the phonon frequency of strained Bi₂Se₃ nanoribbons grown along the 鉄?12虆0鉄?direction. The frequencies of the in-plane E_g² and out-of-plane A_1g¹ modes exhibit a nearly linear blue-shift against bending strain when the nanoribbon is bent along the 鉄?12虆0鉄?direction with the curved {0001} surface. In this case, the phonon deformation potential of the E_g² phonon for 100 nm-thick Bi₂Se₃ nanoribbon is up to 0.94 cm^鈥?/%, which is twice of that in Bi₂Se₃ bulk material (0.52 cm^鈥?/%). Our results may be valuable for the strain modulation of individual topological insulator nanostructures.