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Electron transport in stepped Bi2Se3 thin films
1Faculty of Physics and Center for Nanointegration Duisburg-Essen CENIDE, University of Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany.
Summary
Electron transport in bismuth selenide (Bi₂Se₃) films is affected by surface steps and domain boundaries. Domain boundaries act as scattering sites, influencing conductivity and causing anisotropy.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Surface Science
Background:
- Bismuth selenide (Bi₂Se₃) is a topological insulator with unique electronic properties.
- Understanding electron transport in nanostructured Bi₂Se₃ films is crucial for potential applications.
Purpose of the Study:
- To investigate electron transport mechanisms in stepped Bi₂Se₃ films at the nanoscale.
- To identify the role of surface features like steps and domain boundaries in electron scattering.
Main Methods:
- Scanning tunnelling potentiometry (STP) for nanoscale voltage mapping.
- Scanning tunnelling microscopy (STM) for structural analysis.
- Multi-point probe measurements (2-point probe and 4-point probe) for macroscopic characterization.
Main Results:
- Microscopic STP revealed voltage drops at domain boundaries, indicating they act as electron scatterers.
- Macroscopic measurements confirmed these findings, showing conductivity anisotropy of ~10% parallel and perpendicular to Bi₂Se₃ steps.
- The conductivity of Bi₂Se₃ steps was determined to be approximately 1000 S cm⁻¹.
Conclusions:
- Domain boundaries significantly impede electron transport in Bi₂Se₃ films.
- Anisotropic step distribution leads to measurable electrical anisotropy in the film's conductance.
- The study provides detailed insights into nanoscale electron transport in topological insulator films.
