Surface properties of polycrystalline hydrogenated diamond produced by chemical vapour deposition upon oxidation under UV irradiation are studied. The diamond surfaces were cleaned in vacuum by thermal treatment. They were characterized estimating the electron affinity of the virgin surface by UV photoelectron spectroscopy and controlling the surface composition by X-ray photoelectron spectroscopy. The cleaned surfaces were then exposed to pure oxygen and UV radiation (deuterium lamp). Ozone induced surface oxidation was verified by XPS estimating the oxygen atomic concentration and the presence of specific chemical bonds. Surface oxidation was also verified analyzing the change in the diamond electron affinity. Oxygen was then removed in situ by a series of thermal treatments at increasing temperature. Already at 300 °C a remarkable reduction of the oxygen concentration occurs which persists increasing the annealing temperature. Contemporary, a progressive recovery of the initial electron affinity is also obtained. These effects are observed up to 970 °C, a temperature at which the electron affinity assumes a negative value. Specific chemical reactions are hypothesized to describe the oxidation process and to explain the electronic behaviour of the diamond surface.
Titolo: | In situ thermal treatment of UV-oxidized diamond hydrogenated surface |
Autori Riconosciuti: | |
Autori: | G. Speranza; S. Torrengo; M. Filippi; L. Minati; E. Vittone; A. Pasquarelli; M. Dipalo; E. Kohn |
Data di pubblicazione: | 2010 |
Abstract: | Surface properties of polycrystalline hydrogenated diamond produced by chemical vapour deposition upon oxidation under UV irradiation are studied. The diamond surfaces were cleaned in vacuum by thermal treatment. They were characterized estimating the electron affinity of the virgin surface by UV photoelectron spectroscopy and controlling the surface composition by X-ray photoelectron spectroscopy. The cleaned surfaces were then exposed to pure oxygen and UV radiation (deuterium lamp). Ozone induced surface oxidation was verified by XPS estimating the oxygen atomic concentration and the presence of specific chemical bonds. Surface oxidation was also verified analyzing the change in the diamond electron affinity. Oxygen was then removed in situ by a series of thermal treatments at increasing temperature. Already at 300 °C a remarkable reduction of the oxygen concentration occurs which persists increasing the annealing temperature. Contemporary, a progressive recovery of the initial electron affinity is also obtained. These effects are observed up to 970 °C, a temperature at which the electron affinity assumes a negative value. Specific chemical reactions are hypothesized to describe the oxidation process and to explain the electronic behaviour of the diamond surface. |
Volume: | 604 |
Pagina iniziale: | 753 |
Pagina finale: | 761 |
Digital Object Identifier (DOI): | 18860 10.1016/j.susc.2010.01.004 S0039-6028(10)00019-1 |
URL: | http://www.dfs.unito.it/solid/PUBBLICAZIONI/pub_generale.html#ANNO2010 |
Parole Chiave: | Diamond; Ultraviolet photoelectron spectroscopy; Oxidation Surface chemical reaction; Surface electronic phenomena; Thermal desorption |
Rivista: | SURFACE SCIENCE |
Appare nelle tipologie: | 03A-Articolo su Rivista |