Interaction of Oxygen with TiN(001): N O Exchange and Oxidation Process
This work presents a detailed experimental and theoretical study of the oxidation of TiN(001) using a combination of synchrotron-based photoemission and density functional theory (DFT). Experimentally, the adsorption of O{sub 2} on TiN(001) was investigated at temperatures between 250 and 450 K. At the lowest temperature, there was chemisorption of oxygen (O2,gas{yields}2Oads) without significant surface oxidation. In contrast, at 450 K the amount of O{sub 2} adsorbed increased continuously, there was no evidence for an oxygen saturation coverage, a clear signal in the Ti 2p core level spectra denoted the presence of TiO{sub x} species, and desorption of both N{sub 2} and NO was detected. The DFT calculations show that the adsorption/dissociation of O{sub 2} is highly exothermic on a TiN(001) substrate and is carried out mainly by the Ti centers. A high oxygen coverage (larger than 0.5 ML) may induce some structural reconstructions of the surface. The exchange of a surface N atom by an O adatom is a highly endothermic process ({Delta}E=2.84 eV). However, the overall oxidation of the surface layer is thermodynamically favored due to the energy released by the dissociative adsorption of O{sub 2} and the formation of N{sub 2} or NO. Both experimental and theoretical results lead to conclude that a TiN+mO{sub 2}{yields}TiO{sub x}+NO reaction is an important exit channel for nitrogen in the oxidation process.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 930540
- Report Number(s):
- BNL-80614-2008-JA; JCPSA6; TRN: US200904%%578
- Journal Information:
- Journal of Chemical Physics, Vol. 126; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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