Theoretical study of Cs adsorption on GaN(0001) surface

► Using density functional theory with a plane-wave ultrasoft pseudopotential method based on first-principles calculations, we have found that the most stable positions of Cs adatoms on (2×2)GaN(0001) surface are at N-bridge and H3 sites for 1/4 monolayer coverage. ► The change of adsorption energi...

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Bibliographic Details
Published in:Applied surface science 2012-07, Vol.258 (19), p.7425-7429
Main Authors: Du, Yujie, Chang, Benkang, Wang, Xiaohui, Zhang, Junju, Li, Biao, Wang, Meishan
Format: Article
Language:English
Subjects:
Adsorption
Adsorption energy
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Condensed matter: structure, mechanical and thermal properties
Cross-disciplinary physics: materials science
rheology
Cs/GaN adsorption system
Density functional theory
Electronic structure
Exact sciences and technology
First-principles
Gallium
Mathematical analysis
Nuclear power generation
Physics
Saturation
Surface chemistry
Work function
Work functions
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Summary:► Using density functional theory with a plane-wave ultrasoft pseudopotential method based on first-principles calculations, we have found that the most stable positions of Cs adatoms on (2×2)GaN(0001) surface are at N-bridge and H3 sites for 1/4 monolayer coverage. ► The change of adsorption energies and the change of work function with coverage from 1/4 to 1 monolayer are analyzed, and the reason for those changes is also analyzed. ► These results provide a theoretical reference for the activation experiment of negative electron affinity GaN optoelectronic cathodes. The adsorption characteristics and change in work function of Cs on a (2×2) GaN(0001) surface with a coverage from 1/4 to 1 monolayer (ML) have been investigated using density functional theory with a plane-wave ultrasoft pseudopotential method based on first-principles calculations. The results show that the most stable positions of Cs adatoms on GaN(0001) surfaces are at N-bridge and H3 sites for 1/4 ML coverage. As the Cs atomic coverage is increased, adsorption energy and stability reduce and achieve saturation when the Cs adatom coverage is 3/4 ML. The transfer of Cs6s electrons to Ga atoms in the outermost layer decreases the work function of the system.
ISSN:0169-4332
1873-5584
DOI:10.1016/j.apsusc.2012.04.055