Investigation of the Electronic Structure of Stanene on Bi2Te3 by Arpes
Hsiao Yu Lin1*, K. H. Chen1, S. W. Huang1, C. C. Chen1, J. W. Liu4, W. C. Fan4, W. C. Chou4, C. M. Cheng3, M. Hong2, J. Raynien Kwo1
1Department of physics, National Tsing Hua University, Hsinchu, Taiwan
2Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, Taiwan
3National Synchrotron Radiation Research Center, Hsinchu, Taiwan
4Department. of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
* presenting author:Hsiao Yu Lin,
One monolayer (111) -orientated α-phase Sn is a buckled-honeycomb structure, similar to graphene. 2-D group-IV materials including graphene, silicene, germanene and stanene have attracted enormous interest, and stanene is of special interest owing to its outstanding properties. For instance, stanene could support a large-gap 2-D quantum spin Hall (QSH) state with strong SOC, and thus enables the dissipationless electric conduction at room temperature (RT), and near-RT quantum anomalous Hall (QAH) effect, etc.
We have employed high quality Bi2Te3 thin film as a template to grow 2-D stanene film with a small lattice mismatch. RHEED oscillation was used to determine the deposition time of Sn on Bi2Te3. After stanene growth, the in-plane lattice constant of the ultrathin Sn film is found to be in close match with that of the Bi2Te3 substrate according to the spacing of RHEED diffraction lines and LEED diffraction spots. This indicates that stanene is strained by Bi2Te3.
The ARPES spectrum of stanene on Bi2Te3 around Γ point shows two hole bands originated from stanene. In addition, a Dirac-like 2D state is observed around Γ point, different from previous study.1 Energy dependent spectra were taken to confirm that it is 2D state. The origin of the 2D state could be from the reaction between Bi2Te3 and stanene. XPS spectra of Sn 3d and Bi 4d core level of stanene/Bi2Te3(111) show Sn reacts with Bi atoms, as opposed to with Te atoms at the top surface. Therefore, Dirac-cone at the K-point of stanene/Bi2Te3 (111) was not observed, due to reactions between stanene and Bi2Te3.
Furthermore, we attempt to grow stanene on the CdTe (111) substrate due to its smaller lattice mismatch with stanene and hexagonal surface Bravais lattice. Moreover, chemical reactions are expected to be less between Cd and Sn, and no bulk bands resulting from CdTe(111) around binding energy=0-1eV at K point.2 According to above reasons, a Dirac cone is expected to be at K point in stanene/ CdTe(111). The ARPES spectrum of stanene on CdTe(111) is now underway.

1. F. -F. Zhu et al., Nat. Mater. 14, 1020 (2015).
2. J. Ren et al., Phys. Rev. B 91, 235303 (2015).

Keywords: Topological insulator, Stanene, ARPES