Tuning the Fermi level with topological phase transition by internal strain in a topological insulator Bi2Se3 thin film. Issue 2 (11th December 2015)

• Record Type: Journal Article
• Authors: Kim, Tae-Hyeon; Jeong, KwangSik; Park, Byung Cheol; Choi, Hyejin; Park, Sang Han; Jung, Seonghoon; Park, Jaehun; Jeong, Kwang-Ho; Kim, Jeong Won; Kim, Jae Hoon; Cho, Mann-Ho
• Is Part Of: Nanoscale. Volume 8:Issue 2(2016)
• Page Start: 741
• Page End: 751
• Publication Date: 2015-12-11
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c5nr06086a
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : Strain-dependent Bi2 Se3 films of various thickness are grown via a self-organized ordering process. As the film thickness decreases from 8 to 2 QL, significant changes of the Fermi level and bandgap were observed. Our results provides an understanding of critical effect on the change in band structure caused by the structural deformation in a topological insulator. Abstract : In a three-dimensional topological insulator Bi2 Se3, a stress control for band gap manipulation was predicted but no systematic investigation has been performed yet due to the requirement of large external stress. We report herein on the strain-dependent results for Bi2 Se3 films of various thicknesses that are grown via a self-organized ordering process. Using small angle X-ray scattering and Raman spectroscopy, the changes of d -spacings in the crystal structure and phonon vibration shifts resulted from stress are clearly observed when the film thickness is below ten quintuple layers. From the UV photoemission/inverse photoemission spectroscopy (UPS/IPES) results and ab initio calculations, significant changes of the Fermi level and band gap were observed. The deformed band structure also exhibits a Van Hove singularity at specific energies in the UV absorption experiment and ab initio calculations. Our results, including the synthesis of a strained ultrathin topological insulator, suggest a new direction for electronic and spintronic applications for the future.