Variation of the permittivity and conductivity of a single crystalline /spl alpha/-SiO/sub 2/ with the surface charge density

The complex permittivity and conductivity can be determined by using the technique that is based on cavity perturbation theory. A rectangular cavity working in the TE/sub 103/ mode at a frequency of 9.273 GHz has been used. Rectangular Z cut /spl alpha/-SiO/sub 2/ samples are inserted in the resonator at a maximum electric field region. The depolarisation factors are assumed to be known, In order to remove residual charge samples were systematically fired at 800/spl deg/C. Each sample is charged on its free upper surface by using an electron beam radiation of 30 kV. The surface charge density /spl sigma//sub ch/ is controlled by defocusing the incident beam and evaluated by using the mirror method. Electrons are trapped on defects and increase the polarisation of the charged dielectric. The permittivity and the conductivity are measured.