Ab-initio study of the Y adsorption and YN formation on the GaN(0001¯): Diffusion pathways and stability. (August 2016)

• Record Type: Journal Article
• Authors: Guerrero-Sánchez, J.; H. Cocoletzi, Gregorio; Rivas-Silva, J.F.; Takeuchi, Noboru
• Is Part Of: Superlattices and microstructures. Volume 96(2016)
• Page Start: 67
• Page End: 74
• Publication Date: 2016-08
• Subjects: Gallium nitride -- Yttrium nitride -- Bilayer formation -- Diffusion pathways -- Surface formation energy; Superlattices as materials -- Periodicals; Microstructure -- Periodicals; Semiconductors -- Periodicals; Superréseaux -- Périodiques; Microstructure (Physique) -- Périodiques; Semiconducteurs -- Périodiques; 621.38152
• DOI: 10.1016/j.spmi.2016.05.007
• Languages: English
• ISSNs: 0749-6036

Abstract

Abstract: Yttrium (Y) adsorption and yttrium nitride (YN) thin film formation on the GaN(000 1 ¯ ) surface are investigated using first principles total energy calculations. Results show that for Ga rich conditions the most stable configuration for Y adsorption is at a Bridge site. Nudged elastic band calculations show that the Y diffusion through the GaN surface is possible with low energy barriers. However, the most stable configuration corresponds to the geometry in which the Y atom migrates in to the first layer, forming an YN pair and displacing a Ga atom to the T4(2) site. Also, it is found that the increase of Y atoms up to a full monolayer is not energetically favorable, then the formation of an Y layer on top of the surface is not possible. However, under N-rich conditions the formation of a cubic-like YN bilayer above the surface becomes stable. Total and partial density of states show that the formation of YN on top of the Ga-terminated surface modify the electronic properties. Nevertheless, metallic behavior remains after YN formation. Highlights: Y atom faces small energy barriers to diffuse through the GaN(000 1 ¯ ) surface. Y migration into the first monolayer may be reached after overcoming a transition state of ∼0.64 eV. Increasing the Y content drives to the formation of a cubic YN bilayer on top of the Ga adlayer terminated surface. Metallic behavior remains after Y incorporation into the surface.