Electrical and impedance properties of MPS structure based on (Cu₂O–CuO–PVA) interfacial layer

In this study, the electrical characteristics of the prepared Au/(Cu₂O–CuO–PVA)/n-Si (MPS) structures have been investigated in detail by using the frequency dependent C–V and G/ω–V measurements by taking into account the interfacial polymer layer, surface states (N_ss), polarization and series resistance (R_s). The electric parameters such as the diffusion potential (V_D), the concentration of donor atoms (N_D), and barrier height (BH) values were obtained from C⁻²–V plots for each frequency and they were found as 0.33 eV, 7.60 × 10¹³cm⁻³, 0.65 eV at 10 kHz and 0.70 eV, 6.99 × 10¹³cm⁻³, 1.02 eV at 3 MHz. The energy dependent profiles of N_ss and their relaxation time (τ) were found by using admittance method and they ranged from 1.09 × 10¹¹ to 1.60 × 10¹¹ eV⁻¹ cm⁻² and 7.75 × 10⁻⁶ to 9.93 × 10⁻⁵ s, respectively. These low values of N_ss are indicated that the (Cu₂O–CuO)-doped PVA interfacial layer considerably enhances the performance of the Au/n-Si (MS) structure and so it can be successfully utilized instead of the traditional insulator/dielectric layer due to its passivized the surface states. The R_s versus V plot was obtained from the C–V and G/ω–V data using Nicollian and Brews method and it shows a distinctive peak, while the magnitude of the peak decreases with increasing frequency, its position shift towards lower or negative bias voltage with decreasing frequency due to the reordering and restructuring of surface states and their relaxation time under applied bias voltage. The impedance measurements were also performed in the wide range of frequency (100 Hz–1 MHz) at room temperature. The equivalent circuit model parameters such as parallel resistor (R_p), capacitor (C_p) and a series resistance (R_s) were calculated from Cole–Cole plots. The values of R_s, R_p and C_p decrease with increases dc voltage. The decrease of R_p is because of the increasing in the number of injected charge carriers into the device.