Variation of the permittivity and conductivity of a single crystalline α-SiO2 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 TE₁₀₃ mode at a frequency of 9.273 GHz has been used. Rectangular Z cut α-SiO₂ 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°C. Each sample is charged on its free upper surface by using an electron beam radiation of 30 kV. The surface charge density σ_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