Electrical and photoresponse properties of CoSO₄-PVP interlayer based MPS diodes

The cobalt sulfate-polyvinylpyrrolidone (CoSO₄-PVP) solution was deposited on n-Si crystal by using spin-coated method. The electrical and photoresponse properties of Au/(CoSO₄-PVP)/n-Si MPS diode were investigated both in the dark and under illumination (100 mW/cm²) level. MPS-type diode exhibits good rectifying behavior in dark condition. The measured reverse current under illumination was found to be higher than dark condition. The MPS diode has also a good response to the illumination and photosensitivity value was found as 5.25 × 10³ for 100 mW/cm². The diode parameters such as n, Φ_b0 and R_s were extracted based on both the thermionic-emission (TE) and Norde method. The current conduction mechanisms of the MPS diode were also analyzed by forward ln(I_F)-ln(V_F) and reverse ln(I_R)-V_R^1/2 plots. Moreover, both the voltage dependence of C and G characteristics were investigated under 1 MHz. The other electrical parameters such as V₀, V_D, N_D, E_F, W_D and Φ_B were extracted from the C⁻²–V characteristics. Besides, the voltage dependence profile of the N_ss was extracted by using dark-illumination capacitance (C_dark-C_ill) measurements at a frequency of 1 MHz. The results suggest that the prepared Au/(CoSO₄-PVP)/n-Si MPS diode can be used in optoelectronic device applications.