Epitaxial Growth of Bi2Te3 Topological Insulator Films by Temperature Gradient Induced Physical Vapor Deposition
Hsin-Yen Lee1*, Yu-Sung Chen2, Yen-Cheng Lin2, Chao-Chun Lee2, Jen-Kai Wu1, Ying-Chen Lee1, Chi-Te Liang1,2, Yuan-Huei Chang1,2
1Department of Physics, National Taiwan University, Taipei, Taiwan
2Institute of Applied Physics, National Taiwan University, Taipei, Taiwan
* presenting author:Hsin-Yen Lee, email:hyli.ai@gmail.com
We report the growth of high quality Bi2Te3 thin films on Al2O3 substrates by using physical vapor deposition. Through a carefully selected temperature gradient on two separately controllable heaters inside a furnace, a twin domain, unstrained film bonded by van der Waals epitaxy between each layer was formed along c-axis orientation, which is confirmed by X-ray diffraction θ-2θ and ϕ scans. The stoichiometry study by X-ray photoelectron spectroscopy shows that the film is clean with minimum surface oxidation and contaminants, and the ratio of the atomic densities between Bi and Te is estimated to be 1.51. Relatively low carrier concentration of n3D = 4.83 × 1018 cm-3 and electron mobility μ = 192.4 cm2/Vs at T = 3 K allowed a clear observation of weak anti-localization effect. Using a traditional 2D localization analysis by HLN equation within 0.4 T, we found a clear evidence of the existence of the topological surface states, and the temperature dependence of the phase coherent length also exhibits a 2D material behavior.

Keywords: Bismuth telluride, Topological insulator, PVD