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Surface terminations control charge transfer from bulk to surface states in topological insulators
Keiki Fukumoto1, Seunghee Lee2, Shin-Ichi Adachi2
1High energy accelerator research organization (KEK), 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan. keiki@post.kek.jp.
Scientific Reports
|May 8, 2024
Summary
Investigating topological insulators (TI), this study reveals that specific surface configurations significantly impact electron dynamics in Dirac surface states (DSS). This finding is crucial for advancing TI-based electronic and optoelectronic devices.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Surface Science
Background:
- Topological insulators (TI) offer potential for advanced electronics due to their Dirac surface states (DSS).
- Electron behavior in DSS is critical for spintronic, thermoelectric, and terahertz device performance.
- Surface atomic configuration homogeneity is not guaranteed in exfoliated 3D TI.
Purpose of the Study:
- To investigate the impact of surface terminating atomic configurations on electron dynamics in 3D TI.
- To understand how surface states influence electron behavior within the Dirac surface state (DSS).
- To correlate specific surface structures with unique electron dynamics for device applications.
Main Methods:
- Experimental examination of electron dynamics at exfoliated Bi2Se3 surfaces with time, space, and energy resolution.
- Comprehensive band structure calculations.
- Analysis of photoexcited electron relaxation pathways and dwell times at the Dirac point.
Main Results:
- Identified a specific Se-terminated surface where DSS is isolated within the bulk band gap.
- Observed that photoexcited electrons relax to DSS and linger at the Dirac point on this particular surface.
- Demonstrated that these distinct DSS characteristics are exclusive to this specific surface termination.
Conclusions:
- Surface terminating atomic configuration critically influences electron dynamics in 3D TI.
- The Se-terminated surface exhibiting isolated DSS offers unique electron behavior for potential device applications.
- Tailoring surface structures is key to harnessing the full potential of topological insulators.
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