Investigation of dielectric properties of Ag-doped ZnO thin films

Abstract

In this study, undoped and Ag-doped ZnO thin films were grown on p-type Si substrates using Sol-Gel spin coating technique at room temperature. Optical properties, such as refractive index (n) and extinction coefficient (k) were determined using the optical data in terms of wavelength and photon energy, respectively. Depending on Ag doping concentration, some changes in optical properties thin films were observed. Also, the frequency and voltage dependence of some dielectric properties of thin films have been evaluated using the admittance spectroscopy method in the wide frequency range of 10 kHz to 1 MHz at room temperature. Experimental results show that the real (ε') and imaginary parts (ε'') of dielectric constants, loss tangent (tanδ), real (M') and imaginary (M'') parts of electric modulus were strong functions of frequency and applied bias voltage in the depletion region. The loss tangent versus applied bias voltage curves shows an increase with increasing frequencies and shifts to applied forward bias region giving a peak at about 3 V. M' and M'' values decreased with increasing frequency and shifts to reverse bias region. In addition, it was determined that a.c. electrical conductivity (σ∗) values of thin films increased with increasing voltage as a function of dielectric loss.