Negative electron affinity from aluminium on the diamond (1 0 0) surface: a theoretical study

Area of Science:

• Materials Science
• Surface Science
• Computational Chemistry

Background:

• Diamond surfaces are crucial for electron emission applications.
• Understanding metal-atom adsorption on diamond is key to optimizing surface properties.
• Negative electron affinity (NEA) surfaces are desirable for efficient electron emission.

Purpose of the Study:

• To investigate the adsorption of aluminium on bare and O-terminated diamond (100) surfaces using density functional theory.
• To determine the adsorption energies and electron affinity of aluminium-covered diamond surfaces.
• To assess the potential of aluminium-diamond systems for thermally stable electron emission.

Main Methods:

• Density functional theory (DFT) calculations.
• Modeling of aluminium adsorption up to 1 monolayer (ML) on diamond (100).
• Analysis of adsorption energies and electron affinity.

Main Results:

• High adsorption energies for aluminium on O-terminated diamond surfaces (up to -6.36 eV/atom).
• Most adsorption sites resulted in negative electron affinity (NEA).
• Largest NEAs observed were -1.47 eV (bare surface, 1 ML) and -1.36 eV (O-terminated surface, 0.25 ML).
• Associated adsorption energies were -4.11 eV and -5.24 eV per Al atom, respectively.

Conclusions:

• Aluminium adsorption on diamond surfaces, particularly O-terminated, exhibits strong binding.
• Controlled aluminium coverage can create thermally stable surfaces with NEA.
• These findings suggest Al-diamond systems are promising for electron emission applications.