Effects of alkali metal adsorption on the structural and field emission properties of graphene

• Published in: Diamond and related materials 2010-11, Vol.19 (11), p.1377-1381
• Main Authors: Qiao, L., Qu, C.Q., Zhang, H.Z., Yu, S.S., Hu, X.Y., Zhang, X.M., Bi, D.M., Jiang, Q., Zheng, W.T.
• Format: Article
• Language: English
• Subjects: Adsorption; Alkali metals; Band structure of solids; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electron and ion emission by liquids and solids; impact phenomena; Electron sources; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Fermi surfaces; Field emission; Field emission, ionization, evaporation, and desorption; Fullerenes and related materials; diamonds, graphite; Graphene; Materials science; Mathematical analysis; Physics; Simulation; Solid surfaces and solid-solid interfaces; Specific materials; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/j.diamond.2010.08.003

We systematically investigate the structural and field emission properties of alkali metal atoms adsorbed on graphene using first-principles density-functional theoretical calculations. The calculated results indicate that the center of the hexagonal ring of graphene is the most stable adsorption site, and the alkali metal atom can stay stably on graphene by donating their charges to graphene, which results in the redistribution of the Mulliken charges on graphene. Also, we explore the effects of alkali metal atom adsorption on the field emission properties of graphene, in which the magnitude of the ionization potential of graphene becomes smaller and the Fermi level increases after adsorption. Moreover, the Cs adsorption on graphene is believed to be the best choice for enhancing the field emission properties. The mechanism of the enhanced field emission has been analyzed in terms of the modification of the density of states and the band structures caused by the adsorption. Our findings suggest that graphene can be applied as field emission electron source material, and the adsorption of alkali metal atoms can improve its emission performance, which will be helpful in the design of functionalized graphene electronic devices. ►The center of the hexagonal ring of graphene is the most stable adsorption site. ►IP of graphene becomes smaller and the Fermi level increases after adsorption. ►Cs adsorption is believed to be the best choice for enhancing the field emission. ►The mechanism has been analyzed by the modification of DOS and band structures.