Determining electrical and dielectric parameters of dependence as function of frequencies in Al/ZnS-PVA/p-Si (MPS) structures

Abstract

We have studied electrical and dielectric parameters of the Al/ZnS-PVA/p-Si structures using admittance measurements. For this aim, capacitance/conductance–voltage (C/G–V) measurements were performed in the frequency range of 10 kHz–5 MHz and voltages (±4 V) by 50 mV steps at 300 K. Experimental results confirmed that both electric and dielectric parameters are strong function of frequency and voltage and they are especially influenced from series resistance (Rs), surface states (Nss) and polarization processes. The values of Rs and Nss which are obtained from the Nicollian and Brews and Hill–Coleman method, respectively, and they are decrease with increasing frequency almost as exponentially. In addition, the values of real and imaginary part of the dielectric constants (e′ and e″) and electric modules (M′ and M″), loss tangent (tanδ), and ac electrical conductivity (σac) were obtained using C and G/ω data as function of applied bias voltage and they are found to a strong functions of frequency. While the values of e′, e″, and tanδ increase with increasing frequency, M′ and σac decrease. Moreover, the e′, e″, tanδ, and σac increase with applied bias voltage, whereas the M′ decreases with increasing applied bias voltage. The M″ versus V plot shows a peak and its position shifts to the right with increasing bias voltage and it disappears at high frequencies. As a result, the change in the e′, e″, tanδ, M′, M″ and σac is a result of restructuring and reordering of charges at the (ZnS-PVA)/p-Si interface under an external electric field or voltage and interface polarization.