Illumination and Voltage Dependence of Electrical Characteristics of Au/0.03 Graphene-Doped PVA/n-Si Structures via Capacitance/Conductance–Voltage Measurements

Au/n-Si (MS) structures with a high dielectric interlayer (0.03 graphene-doped PVA) are fabricated to investigate the illumination and voltage effects on electrical and dielectric properties by using capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements at room temperature and at 1 MHz. Some of the main electrical parameters such as concentration of doping atoms (N_D), barrier height (?_B(C?V)), depletion layer width (W_D) and series resistance (R_s) show fairly large illumination dispersion. The voltage-dependent profile of surface states (N_ss) and resistance of the structure (R_i) are also obtained by using the dark-illumination capacitance (C_dark–C_ill) and Nicollian–Brews methods, respectively. For a clear observation of changes in electrical parameters with illumination, the values of N_D, W_D, ?_B(C?V) and R_s are drawn as a function of illumination intensity. The values of N_D and W_D change almost linearly with illumination intensity. On the other hand, R_s decreases almost exponentially with increasing illumination intensity whereas ?_B(C?V) increases. The experimental results suggest that the use of a high dielectric interlayer (0.03 graphene-doped PVA) considerably passivates or reduces the magnitude of the surface states. The large change or dispersion in main electrical parameters can be attributed to generation of electron-hole pairs in the junction under illumination and to a good light absorption. All of these experimental results confirm that the fabricated Au/0.03 graphene-doped PVA/n-Si structure can be used as a photodiode or a capacitor in optoelectronic applications.