Local electronic structure of doping defects on Tl/Si(111)1x1

Area of Science:

• Surface science
• Condensed matter physics
• Materials science

Background:

• The Thallium/Silicon(111)1×1 surface exhibits 2D electronic bands with Rashba-type spin splitting.
• Understanding atomic-level doping is essential for utilizing spin polarization in such systems.

Purpose of the Study:

• To investigate the atomic structure and electronic properties of two predicted defect types on the Tl/Si(111) surface.
• To correlate theoretical calculations with experimental scanning tunneling microscopy (STM) and photoemission spectroscopy data.

Main Methods:

• Density functional theory (DFT) for structural and electronic property calculations.
• Analysis of spatial charge distributions and local densities of states.

Main Results:

• DFT confirmed the stability of a defect with an extra Si atom and missing Tl atoms, consistent with prior experiments.
• Calculated charge distributions around the extra Si atom matched STM topographies.
• Calculated local densities of states explained STM spectra.
• DFT determined the structure of a defect with an extra Tl atom, showing a ring-like charge distribution.
• Theoretical charge transfer from the extra Tl atom agreed with photoemission measurements.

Conclusions:

• The study successfully characterized atomic defects on the Tl/Si(111) surface using DFT.
• The findings provide atomic-level insights into doping mechanisms relevant for spintronic applications.
• Theoretical results demonstrate strong agreement with experimental observations, validating the computational approach.