The forward and reverse bias current-voltage (I-V), capacitance/conductance-voltage (C/G-V) characteristics of the fabricated Au/PVA (Bi-doped)/n-Si photodiode have been investigated both in dark and under 250 W illumination intensity at room temperature. The energy density distribution profile of N-ss was extracted from the forward bias I-V measurements by taking the voltage dependence of effective barrier height (Phi(e)) and R-s for photodiode both in dark and under 250 W illumination cases. The exponential growth of the N-ss from midgap toward the bottom of the conductance band is very apparent for two cases. The obtained high value of n and R-s were attributed to the particular distribution of N-ss at metal/PVA interface, surface and fabrication processes, barrier inhomogeneity of interfacial polymer layer and the form of barrier height at M/S interface. While the values of C and G/w increase R-s and R-sh decrease under illumination, due to the illumination induced electron-hole pairs in depletion region. The voltage dependent N-ss profile was also obtained from the dark and illumination capacitance at 1 MHz and these values of N-ss are in good agreement. In addition, the fill factor (FF) under 250 W illumination level was found as 28.5% and this value of FF may be accepted sufficiently high. Thus, the fabricated Au/PVA (Bi-doped)/n-Si structures are more sensitive to light, proposing them as a good candidate as a photodiode or capacitance sensor for optoelectronic applications in modern electronic industry. (C) 2012 Elsevier B.V. All rights reserved.