Frequency and voltage dependence dielectric properties, ac electrical conductivity and electric modulus profiles in Al/Co3O4-PVA/p-Si structures

摘要

In this research a simple microwave-assisted method have been used for preparation of cobalt oxide nanostructures. The as-prepared sample has been investigated by UV vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM). On the other hand, frequency and voltage dependence of both the real and imaginary parts of dielectric constants (epsilon', epsilon '') and electric modulus (Mf and M ''), loss tangent (tan delta), and ac electrical conductivity (sigma(ac)) values of Al/Co3O4-PVA/p-Si structures were obtained in the wide range of frequency and voltage using capacitance (C) and conductance (G/co) data at room temperature. The values of epsilon, epsilon '' and tan delta were found to decrease with increasing frequency almost for each applied bias voltage, but the changes in these parameters become more effective in the depletion region at low frequencies due to the charges at surface states and their relaxation time and polarization effect. While the value of sigma is almost constant at low frequency, increases almost as exponentially at high frequency which are corresponding to sigma(dc) and sigma(ac), respectively. The M' and M '' have low values at low frequencies region and then an increase with frequency due to short-range mobility of charge carriers. While the value of M '' increase with increasing frequency, the value of M '' shows two peak and the peaks positions shifts to higher frequency with increasing applied voltage due to the decrease of the polarization and N-ss effects with increasing frequency. (C) 2016 Elsevier B.V. All rights reserved.