60Co γ-ray irradiation effects on dielectric characteristics of tin oxide films of different thicknesses on n-type Si(111) substrates

We have tried to determine the effects of Co-60 gamma irradiation on properties of Au/SnO2/n-Si (MOS) structures such as dielectric constant (epsilon'), dielectric loss (epsilon ''), tangent loss (tan delta) and ac conductivity (sigma(ac)). Three samples were fabricated with different deposition time. The samples were irradiated using a Co-60 gamma-ray source irradiation with the total dose range of 0-500 kGy at room temperature. Capacitance and conductance (C-G- V) measurements were performed at a frequency of 500 kHz in the dark and at room temperature before and after irradiation. The experimental data were analyzed using complex permittivity and electric modulus. The values of epsilon', epsilon '', tan delta and sigma(ac) showed a strong dependence on the applied voltage and irradiation dose. The dielectric properties of MOS structures have been found to be strongly influenced by the presence of dominant radiation-induced defects. Experimental results show that the interfacial polarization contributes to the improvement of dielectric properties of Au/SnO2/n-Si (MOS) Schottky diodes. (C) 2007 Elsevier B.V. All rights reserved.