Electron-trapping and energy localization in insulating materials. Technological impact of space charge electron-beam characterization

The microscopic processes of fracture or breakdown are unknown, the models are contradicted or leave unexplained several observations, the suspected relationships between the electrical properties, the mechanical properties and the charge properties of the dielectrics are not confirmed by characterization of space charges and we do not know how to relate the results to the reliability of the materials. To overcome these difficulties: (1) we apply the energy localization principle used in mechanics and detonics, (2) we replace by electron traps that localize polarization energy, the defects imagined by Griffith in mechanics and dislocations used in detonation to explain the hot spot formation, (3) the effect of strain rates is taken into account because the localized energy is of the order of the binding energies and the trapping and detrapping characteristic times are of the order of the atomic polarization time (10-9 s). We can thus explain by multiphonon processes the transfer of the localized energy towards the bounds and explain the observations which occur when the strain rates are very high, (4) we develop an electron beam technique to measure the extension of the electron trapping domain and the localized energy beyond which a total discharge of the material occurs. These measurements characterize the space charges in the dielectric interfaces where the hot spots are formed. This technique makes it possible to reproduce most of the observations that remained unexplained and to link the measurements made to the properties and reliability of the insulators.