Au/n-GaAs (MS) type Schottky diodes (SDs) were fabricated with and without pure and Gr-doped PVA interlayer to evaluate the effects of Gr-doped PVA interlayer on the basic electrical parameters (i.e. saturation current (I-o), ideality factor (n), barrier height (Phi(Bo)), series (R-s) and shunt resistances (R-sh) both under dark and illuminated conditions (50-200 W), at room temperature. Using different calculation methods (i.e. thermionic emission (TE) model, Ohm's Law and Norde's method), these parameters were obtained from the current -voltage (I -V) data and compared with each other in various conditions. In our research, it is clear that there are a decrease in R-s value and an increase in R-sh value for Gr-doped PVA in comparison with the pure PVA structure under dark and illuminated conditions, therefore rectifier rate (RR = I-F/I-R), is the proof of the quality for diodes, significantly improved. Also, the Phi(Bo) values with interlayer (pure and Gr-doped PVA) are lower than without. Consequently, these results indicate that the PVA (pure and Gr-doped) changed effectively the BH according to other structure and, moreover, Gr-doped PVA layer significantly improved the quality of Au/PVA/n-GaAs structure under dark and illuminated conditions. (C) 2016 Elsevier Ltd. All rights reserved.