The Effect of the Oxygen Concentration on the Zinc Oxide Films Properties Deposited by Magnetron Sputtering

Abstract

The influences of the oxygen concentration variation on the zinc oxide films structural properties were studied. ZnO films were deposited on silicon substrate by rf magnetron sputtering in reactive plasma using a zinc oxide target. They exhibited a c-axis orientation of below 0.32° FWHM of X-ray rocking curves, an extremely high resistivity of 10¹² ?cm and an energy gap of 3.3 eV at room temperature. It was found that a substrate temperature of 100°C, very low gas pressures of 3.35x10^-3 Torr in argon and oxygen mixed gas atmosphere giving to ZnO thin films a good homogeneity and a high crystallinity. Measurements of the ac conductivity properties of ZnO sandwich structures with silver and platinum electrodes are reported. The frequency dependence of the both the ac conductivity and dielectric constant of thin films of ZnO have been investigated in the frequency range 5Khz-13Mhz.

It is shown that the total ac conductivity ; obeys the equations  where s is an index which increases with frequency and decreases with temperature. The dielectric constant, , lies in the range 8–9 at room temperature and is independent of the frequency in the dielectric thin films.

Keywords: ZnO; R.F sputtering magnetron; X-ray diffraction; conductivity; electrical properties; dielectric properties; optical properties.