Charging Phenomena and Charge Compensation in AES on Metal Oxides and Silica

Abstract

Charging processes on the bulk oxides Al2O3, ZrO2 and SiO2 occurring during Auger Electron Spectroscopy (AES) are studied. All samples experience a negative charge-up under the following parameters: electron beam energy >1 keV, current density >10-2 A cm-2 and different angles of incidence. The samples show strong history effects as a function of previous irradiation damage. For charge compensation, Environmental Auger Electron Spectroscopy with O2 gas is applied; several traditional methods were applied for comparison. Charging of SiO2 and ZrO2 could be reduced considerably in an O2 environmental pressure of <5×10-8 Torr. Charging of Al2O3 could be compensated completely in this oxygen environment. It is shown that for the compensation of the electron beam effects, including electron-stimulated desorption and carbon contamination of the surface, an O2 atmosphere of 5×10-8 Torr is more efficient than using an auxiliary electron gun or low-energy positive ions. It is also more efficient than an Ar environment of 1×10-4 Torr. © 1997 John Wiley & Sons, Ltd.