title: Atomic layer deposition of 1D and 2D nickel nanostructures on graphite.
abstract: One-dimensional (1D) nanowires (NWs) and two-dimensional (2D) thin films of Ni were deposited on highly ordered pyrolytic graphite (HOPG) by atomic layer deposition (ALD), using NH3as a counter reactant. Thermal ALD using NH3gas forms 1D NWs along step edges, while NH3plasma enables the deposition of a continuous 2D film over the whole surface. The lateral and vertical growth rates of the Ni NWs are numerically modeled as a function of the number of ALD cycles. Pretreatment with NH3gas promotes selectivity in deposition by the reduction of oxygenated functionalities on the HOPG surface. On the other hand, NH3plasma pretreatment generates surface nitrogen species, and results in a morphological change in the basal plane of graphite, leading to active nucleation across the surface during ALD. The effects of surface nitrogen species on the nucleation of ALD Ni were theoretically studied by density functional theory calculations. Our results suggest that the properties of Ni NWs, such as their density and width, and the formation of Ni thin films on carbon surfaces can be controlled by appropriate use of NH3.
authors.affiliation: Department of Electrical Engineering, Stanford University, Stanford, CA 94305, United States of America.
authors.forename: Seung Wook
authors.initials: SW
authors.lastname: Ryu
authors.forename: Jaehong
authors.initials: J
authors.lastname: Yoon
authors.forename: Hyoung-Seok
authors.initials: HS
authors.lastname: Moon
authors.forename: Bonggeun
authors.initials: B
authors.lastname: Shong
authors.forename: Hyungjun
authors.initials: H
authors.lastname: Kim
authors.forename: Han-Bo-Ram
authors.initials: HB
authors.lastname: Lee