Phase Transformation-Induced Quantum Dot States on the Bi/Si(111) Surface

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanoscience

Background:

• Controllable quantum dot states (QDSs) are crucial for downscaling electronic devices.
• Existing methods for creating QDSs face challenges in precise size and state control.
• Surface reconstruction engineering offers potential for novel quantum dot system implementation.

Purpose of the Study:

• To report a novel phase transition-induced quantum dot (QD) system.
• To demonstrate controllable QDS implementation on the √3 × √3-Bi/Si(111) surface.
• To investigate the mechanism and kinetics of QD formation and manipulation.

Main Methods:

• Utilized scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) for characterization.
• Employed density functional theory (DFT) calculations to verify experimental findings.
• Investigated the effect of thermal annealing on bismuth phase transformation for QD manipulation.

Main Results:

• Achieved a phase transition-induced QD system on the √3 × √3-Bi/Si(111) surface reconstruction.
• Demonstrated manipulation of QD size down to 2 nm via Bi phase transformation triggered by annealing at 700 K.
• Verified the structure, energy dispersion, and size effect on band gap of the QDs.

Conclusions:

• The phase transition strategy provides a novel approach for implementing controllable QDSs.
• The developed empirical analytical model can predict the transformation kinetics of the QD system.
• This work paves the way for advanced nanoscale electronic devices utilizing precisely engineered QDs.