Abstract
Chemical, compositional, and electronic changes induced by 3-keV sputtering in have been quantitatively studied by use of x-ray photoemission spectroscopy. It is shown that 3-keV bombardment leads to a gradual buildup of an oxygen depletion layer which has been quantitatively characterized by its thickness (∼1.2 nm), averaged composition (∼ZrO), and in-depth distribution of the different oxide phases that originate during the process. In addition, the electronic distribution at the valence band of both thermally grown and -bombarded was also determined by x-ray photoemission spectroscopy. Thermally grown was shown to exhibit significant photoemission in the band gap, probably due to defects. bombardment of those surfaces caused a broadband emission at 2.3 eV above the top of the valence band as well as significant changes in the O 2p region of the valence band which are associated with the above-mentioned changes in surface composition. The Zr 4d contribution to the valence band of the altered layer could also be estimated. This contribution increases with sputtering and accounts not only for the whole emission band in the gap but also significantly for the photoemision in the O 2p energy range.
- Received 13 June 1991
DOI:https://doi.org/10.1103/PhysRevB.45.1391
©1992 American Physical Society