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

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/omega-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/omega-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 (N (D)), Fermi energy level (E (F)), barrier height (I broken vertical bar(B)), and series resistance (R (s)) of the structure were obtained as a function of frequency and voltage. While the value of N (D) decreases with increasing frequency almost as exponentially, the value of depletion width (W (D)) increases. The values of C and G/omega increase with decreasing frequency because the surface states (N (ss)) are able to follow the alternating current (AC) signal, resulting in excess capacitance (C (ex)) and conductance (G (ex)/omega), which depends on their relaxation time and the frequency of the AC signal. The voltage-dependent profiles of N (ss) were obtained from both the high-low frequency capacitance and Hill-Colleman methods. The other important parameter R (s) of the structure was also obtained from the Nicollian and Brews methods as a function of voltage.