THE ROLE OF THE AUGER MECHANISM IN THE RADIATION-DAMAGE OF INSULATORS

The ionization damage associated with electron and X-ray irradiation o f insulating specimens during their investigation by various technique s (EM, AES, XPS, etc) is considered from the point of view of the Auge r mechanism. This damage results from the Auger electron transport thr ough the specimen and more specifically from the Auger cascade in the excited atom. After electronic rearrangements, this cascade finally le aves electron vacancies in the uppermost allowed states of the valence band. It is shown that these vacancies may explain various experiment al results such as the stimulated desorption of ionic species in halid es and oxides as well as the atomic displacements in covalent crystals . A possible way to quantify these effects is shown for the case of X- ray irradiation and for the case of electron irradiation. In the two c ases, the correlation between the microscopic mechanisms and their mac roscopic consequences, from the point of view of charging effects, is pointed out for the first time. Finally various positive aspects of th ese effects are outlined. They concern some new methods of characteriz ation and of elaboration in materials science.