© 2020, Springer-Verlag GmbH Germany, part of Springer Nature.Al/p-Si and Al/(carbon nanofiber–PVP)/p-Si diodes were produced using a p-type silicon wafer with 10 Ω cm resistivity to determine the polymer interlayer effects on device characteristics. To assess whether carbon nanofiber–PVP interlayer is beneficial for electrical performance, the current–voltage (I–V) and the impedance–voltage (Z–V) measurements were performed in wide range of voltage. Thus, electrical parameters such as series resistance, barrier height, and ideality factor were derived from the forward bias Ln (IF)–VF and Cheung’s functions, so that they are compared and voltage dependence of them is explored. Later, the values of intercept voltage, width of depletion layer, doping acceptor atom concentration, and barrier height were also extracted from C−2–V data at 1 MHz and then results were compared with each other. The surface states and their energy profile were also extracted from the IF–VF characteristics by considering barrier height (BH) and n is voltage dependent as well. Experimental results indicate that the carbon nanofiber–PVP interlayer decreases surface states (Nss), series resistance (Rs) and leakage current, whereas it increases rectifying ratio and shunt resistance. Hence, such polymeric interlayer material forms an interesting alternative to conventional oxide layer due to some advantages of polymers such as desirably low values of cost, weight, and energy consumption.