Charge trapping and charge compensation during Auger electron spectroscopy on SiO2

Abstract

It is well known that radiolysis, induced by the electron bombardment, leads to different defects in SiO2, but little is known about the trapping behavior of these defects. In this article, the charging behavior and the depth profiles of the irradiation damage introduced by electron bombardment are studied with Auger electron spectroscopy (AES). For charge reduction an environmental AES using O2 (up to 8×10−8 Torr) and specimen heating are applied. In environmental AES, a strong charge reduction is observed, and the importance of the environment for charge compensation reveals a correlation with electron stimulated desorption. By heating the sample, a strong charge reduction takes place above 500 °C; complete charge compensation can be expected by heating the sample above 700 °C in an O2 environment of 5×10−8 Torr. We suggest that E′ centers, nonbridging oxygen hole centers, and peroxy radicals, are responsible for the efficient trapping of electrons. The observed discharging is believed to be related to the annealing of the defects.