Silicon and germanium terminated (0 0 1)-(2 [Formula: see text] 1) diamond surface
J M A Beattie1, J P Goss1, M J Rayson1
1School of Engineering, University of Newcastle, Newcastle upon Tyne, United Kingdom, NE1 7RU.
Summary
Stable silicon and germanium layers on diamond surfaces are crucial for field-emission and electronic devices. Specific coverages (67% and 75%) create stable surface structures with unique electronic properties, explained by spd-covalent bonding.
Area of Science:
- Materials Science
- Surface Science
- Computational Chemistry
Background:
- Chemical termination of diamond surfaces is key for advanced applications like field emission and electronics.
- Ultra-thin silicon (Si) and germanium (Ge) layers on diamond surfaces exhibit intriguing electronic states.
- Understanding these surface states is vital for controlling diamond's electronic properties.
Purpose of the Study:
- To investigate the stability and electronic properties of silicon and germanium on diamond (001) surfaces using density-functional simulations.
- To determine optimal surface coverages for stable Si/Ge on diamond structures.
- To explain the origin of observed surface states and their contribution to electronic properties.
Main Methods:
- Density-functional theory (DFT) simulations were employed.
- A range of silicon and germanium coverages on the diamond (001) surface were simulated.
- Geometries, adsorption energies, and electron affinities of surface structures were calculated.
Main Results:
- Surface coverages with crystallogen:carbon ratios of 67% and 75% were found to be the most stable.
- These stable coverages explain the presence of an occupied band approximately 1.7 eV below the diamond valence band top.
- The resonant surface state originates from spd-covalent bonding between adsorbates and the diamond surface.
Conclusions:
- Specific silicon and germanium coverages (67% and 75%) provide stable terminations for the diamond (001) surface.
- These stable structures lead to unique electronic properties, including a resonant state within the band gap.
- The findings offer insights into controlling diamond surface electronic properties for device applications.
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