Tailoring Kinetics on a Topological Insulator Surface by Defect-Induced Strain: Pb Mobility on Bi2Te3.
Heteroepitaxial structures based on Bi2Te3-type topological insulators (TIs) exhibit exotic quantum phenomena. For optimal characterization of these phenomena, it is desirable to control the interface structure during film growth on such TIs. In this process, adatom mobility is a key factor. We demonstrate that Pb mobility on the Bi2Te3(111) surface can be modified by the engineering local strain, ε, which is induced around the point-like defects intrinsically forming in the Bi2Te3(111) thin film grown on a Si(111)-7 × 7 substrate. Scanning tunneling microscopy observations of Pb adatom and cluster distributions and first-principles density functional theory (DFT) analyses of the adsorption energy and diffusion barrier Ed of Pb adatom on Bi2Te3(111) surface show a significant influence of ε. Surprisingly, Ed reveals a cusp-like dependence on ε due to a bifurcation in the position of the stable adsorption site at the critical tensile strain εc ≈ 0.8%. This constitutes a very different strain-dependence of diffusivity from all previous studies focusing on conventional metal or semiconductor surfaces. Kinetic Monte Carlo simulations of Pb deposition, diffusion, and irreversible aggregation incorporating the DFT results reveal adatom and cluster distributions compatible with our experimental observations.
National Laboratory of Solid State Microstructures, School of Physics, Nanjing University , Nanjing 210093, P. R. China.
Wen-Kai
WK
Huang
National Laboratory of Solid State Microstructures, School of Physics, Nanjing University , Nanjing 210093, P. R. China.
Kai-Wen
KW
Zhang
National Laboratory of Solid State Microstructures, School of Physics, Nanjing University , Nanjing 210093, P. R. China.
Chao-Long
CL
Yang
National Laboratory of Solid State Microstructures, School of Physics, Nanjing University , Nanjing 210093, P. R. China.|Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, P. R. China.
Haifeng
H
Ding
National Laboratory of Solid State Microstructures, School of Physics, Nanjing University , Nanjing 210093, P. R. China.|Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, P. R. China.
Xiangang
X
Wan
National Laboratory of Solid State Microstructures, School of Physics, Nanjing University , Nanjing 210093, P. R. China.|Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, P. R. China.
Shao-Chun
SC
Li
Department of Physics and Astronomy, Iowa State University , Ames, Iowa 50011, United States.|Ames Laboratory- U.S. Department of Energy, Iowa State University , Ames, Iowa 50011, United States.
James W
JW
Evans
Department of Physics and Astronomy, Iowa State University , Ames, Iowa 50011, United States.|Ames Laboratory- U.S. Department of Energy, Iowa State University , Ames, Iowa 50011, United States.
Yong
Y
Han
Surface strain; density functional theory calculations; heteroepitaxial film growth; kinetic Monte Carlo simulations; surface adsorption and diffusion; topological insulator surface