Determination of electrical parameters of 3 % graphene-doped polyvinylalcohol (PVA) interfacial layered Au/n-Si (MPS) structure irradiated with various doses of beta (β) by using impedance measurements

Abstract

In this study, Schottky barrier diodes (SBDs) incorporating a polymer interface layer composed of 0.03 graphene (Gr): polyvinyl alcohol (PVA) were fabricated. Then, the electrical characteristics of these structures were analyzed using capacitance-voltage (C-V) and conductance-voltage (G/ω-V) measurements at 1 MHz under varying beta radiation doses. The impact of radiation on their electrical characteristics was evaluated at room temperature as a function of dose. The experimental results revealed a progressive decrease in both capacitance and conductance of the Au/(0.03 Gr: PVA)/n-Si (MPS) structure with the increase in beta radiation dose. The C-V curves exhibited a distinct peak in the voltage range between −0.8 V and 1.8 V under radiation exposure, which was attributed to the unique distribution of interfacial states (N_ss) within the polymer layer and the energy gap. Furthermore, the C-G/ω-V characteristics indicated the structure's inductive behavior, which disappeared after exposure to a 10 kGy radiation dose. Analysis of the reverse-bias C⁻²-V plots before and after beta radiation demonstrated linearity over a broad voltage range, enabling the calculation of key parameters such as diffusion potential (V_D), donor concentration (N_D), depletion width (W_D), Fermi level (E_F), and barrier height (Ф_B). The MPS structure's interfacial state density (N_ss) before radiation (0 kGy) was determined using the high-low frequency capacitance difference method (C_HF-C_LF), and it was found to be on the order of ∼10¹³ eV⁻¹cm⁻³, after exposure to a beta radiation dose of 22 kGy, the interfacial state density significantly decreased to ∼10¹⁰ eV⁻¹cm⁻³, which was determined through capacitance difference analysis (C_Before −C_After). This notable reduction in N_ss was attributed to the passivation effect of the polymer interface layer (0.03 Gr: PVA). The series resistance (R_s) of the MPS structure, which was influenced by beta radiation, was evaluated using the admittance method. R_s had a more pronounced effect in the accumulation region, whereas N_ss was more significant in the depletion region. Despite the influence of beta radiation on the electrical properties, there were no substantial defects or structural distortions that could impair the performance of the Au/(0.03 Gr: PVA)/n-Si (MPS) structure. These findings suggest that Schottky barrier diodes with polymer interface layers are promising candidates for use in MPS-type detectors, and they offer a viable alternative to traditional MIS/MOS-type detectors.