Examination of Electrical and Dielectric Parameters of Au/n-Si Schottky Barrier Diodes (SBDs) with Organic Perylene Interlayer Using Impedance Measurements Under Various Illumination Intensities

This study examines a metal–semiconductor structure with an organic perylene interlayer by measuring capacitance (C) and conductance (G/w) versus voltage under various lighting conditions and illumination levels (dark and 50–250 mW cm⁻²) in a wide range of voltage (±5 V). The increase in illumination results in an increase in capacitance and conductance values in the depletion and accumulation regions due to surface-state illumination (N_ss). The barrier height ( \(\Phi_{B}\) ${\mathrm{\Phi }}_B$ ) decreased from 1.617 eV (in the dark) to 0.543 eV (under 250 mW cm⁻²). The C–V plot demonstrates peak behavior before going negative at the accumulation region. As the illumination intensity increases, the peak magnitude also increases, and concurrently, its position shifts towards the densely accumulated region due to the illumination-induced changes in surface states (N_ss) and the subsequent reordering/restructuring of these states. The lowest value of capacitance corresponds to the highest value of conductance, and the negative value of C decreases as illumination increases. The Hill–Coleman and Nicollian–Brews methods were used to obtain the voltage/illumination-dependent profile of N_ss and R_s, respectively. The relaxation mechanism of the SBD was also explained using electric modulus formalisms. The slope of ln(σ_AC)–ln(P) plot changed from 0.474 and 0.824 and so Au/C₂₀H₁₂/n-Si SBD can be used in photonic applications.