Domain sensitive contrast in photoelectron emission microscopy.

Area of Science:

• Surface Science
• Materials Science
• Condensed Matter Physics

Background:

• The Si(100) surface exhibits unique reconstructions, (2x1) and (1x2), crucial for surface chemistry.
• Understanding adsorbate behavior on semiconductor surfaces is key for electronic device development.

Purpose of the Study:

• To investigate the adsorption of cesium (Cs) on the reconstructed Si(100) surface.
• To analyze the polarization-dependent behavior of Cs adsorption using photoelectron emission microscopy.
• To elucidate the underlying electronic and geometric structures governing the observed phenomena.

Main Methods:

• Photoelectron Emission Microscopy (PEEM) utilizing linearly polarized green laser light.
• Density-Functional Theory (DFT) calculations for surface structure and electronic properties.
• Analysis of polarization-dependent contrast in PEEM images.

Main Results:

• Observed a clear polarization-dependent contrast between the (2x1) and (1x2) reconstructed domains of Si(100) upon Cs adsorption.
• DFT calculations successfully reproduced the geometric and electronic structure of the Cs/Si(100) interface.
• The observed contrast was quantitatively explained by dipole selection rules governing photoemission matrix elements.

Conclusions:

• Cesium adsorption on Si(100) leads to distinct surface domain contrasts observable with PEEM.
• The electronic and geometric structure, as determined by DFT, dictates the polarization dependence.
• Photoemission selection rules provide a fundamental explanation for the observed surface anisotropy.