On the Frequency and Voltage-Dependent Profiles of the Surface States and Series Resistance of Au/ZnO/n-Si Structures in a Wide Range of Frequency and Voltage

Abstract

In order to interpret the electrical characteristics of fabricated Au/ZnO/n-Si structures as a function of frequency and voltage well, their capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements were carried out in a wide range of frequencies (0.7 kHz–2 MHz) and voltages (± 6 V) by 50 mV steps at room temperature. Both the C–V and G/ω–V plots have reverse, depletion, and accumulation regions such as a metal–insulator/oxide semiconductor (MIS or MOS) structures. The values of doped-donor atoms (ND), Fermi energy level (EF), barrier height (ΦB), and series resistance (Rs) of the structure were obtained as a function of frequency and voltage. While the value of ND decreases with increasing frequency almost as exponentially, the value of depletion width (WD) increases. The values of C and G/ω increase with decreasing frequency because the surface states (Nss) are able to follow the alternating current (AC) signal, resulting in excess capacitance (Cex) and conductance (Gex/ω), which depends on their relaxation time and the frequency of the AC signal. The voltage-dependent profiles of Nss were obtained from both the high–low frequency capacitance and Hill-Colleman methods. The other important parameter Rs of the structure was also obtained from the Nicollian and Brews methods as a function of voltage. © 2017, The Minerals, Metals & Materials Society.