Charge trapping and ac conductivity in Amorphous Silicon Oxide

In this paper we have studied the effect of accelerated thermal ageing on the electrical properties of amorphous silicon oxide films a-SiO2. In order to study the charge trapping phenomenon in this material, we have performed the mirror method using a secondary Electron Microscope (SEM). This method consists to inject a negative space charge in the specimen with a high energy electron beam. Results show that trapped charges increase with thermal ageing time. Dielectric investigations performed in the frequency range between 20 Hz and 1 MHz, showed that the relative permittivity increases with thermal ageing time. The ac conductivity has been found to follow the Jonsher law σacαωn. The decrease of ac conductivity has been interpreted.