Electron-impact-induced oxidation of Al(111) in water vapor: Relation to the Cabrera-Mott mechanism

Abstract

The oxidation of an Al͑111͒ single-crystal surface induced by 100 eV electron bombardment in water vapor at room temperature has been studied using x-ray photoemission spectroscopy and electron-energy-loss spectroscopy. Electron bombardment significantly increases the growth rate and changes the observed growth-rate law in comparison to the oxidation without the electron beam. The aluminum oxide film grows with linear rather than parabolic time-dependent kinetics up to a thickness of about 25 Å. After reaching this thickness, the growth rate slows down significantly. During oxidation the oxide film becomes electrically charged on its surface and the normal electric field in the oxide remains constant. The results are discussed in the framework of a Cabrera-Mott type oxidation mechanism.

X-ray photoelectron spectroscopy and secondary electron yield analysis of Al and Cu samples exposed to an accelerator environment

“…These aspects have been discussed by a number of authors, and the interested reader is referred to a number of works on the subject. [11][12][13][14][15][16][17][18] Ebringer and Yates have studied the oxidation of Al metal by water vapor with and without the presence of a 100 eV electron beam. 14 They showed that the oxide film forms via a Cabrera-Mott mechanism, where the electric field established by surface oxygen anions promotes diffusion of anions toward the metal interface and/or metal cations to the surface.…”

Interaction of nanostructured metal overlayers with oxide surfaces

“…This reaction mechanism has been found to be active in many oxidation experiments [116][117][118][121][122][123][124].…”

Tuning the Limiting Thickness of a Thin Oxide Layer on Al(111) with Oxygen Gas Pressure

“…It has been shown that a significant impact on the oxidation kinetics can be achieved by either directly applying an external electric field [3][4][5][6][7][8][9][10] or electron bombardment of the oxide surface [11][12][13]. We demonstrate here that the actual value of the self-generated electrostatic potential (designated as the kinetic potential [14]) can deviate from the Mott potential and is tunable by varying the oxygen pressure during oxidation which provides control of the limiting thickness of the oxide film.…”