A Comparative Study on Electrical Characteristics of Au/N-Si Schottky Diodes, with and Without Bi-Doped PVA Interfacial Layer in Dark and Under Illumination at Room Temperature

Abstract

In order to see the effect of Bi-doped PVA interfacial layer on electrical characteristics, both Au/n-Si (MS) and Au/Bidoped PVA/n-Si (MPS) type Schottky barrier diodes (SBDs) were fabricated, and their main electrical parameters were investigated using current-voltage (I-V) and capacitance-voltage (C-V) measurements, in dark and under illumination at room temperature. Forward bias semi-logarithmic I-V plots of these SBDs show two distinct linear regions, with different slopes in the low and intermediate voltage region. Such behavior in I-V plots was explained by two parallel diodes model. Experimental results show that the ideality factor (n), barrier height (φb), series and shunt resistances (Rs and Rsh), and the density of interface states/traps (Nss) are strong functions of illumination level and applied bias voltage. The Rs values were determined from the I-V characteristics, by using both Ohm’s law. The energy distribution profile of Nss was also obtained from the forward bias I-V characteristics, by taking into account voltage dependent barrier height (φe) and ideality factor (n). It was found that Bi-doped PVA layer lead to a considerable decrease in the leakage current, Rs and Nss and increase in Rsh and rectifier rate (RR=IF/IR). In conclusion, a thin Bi-doped PVA interfacial layer, considerably improved the diode performance, both in dark and under illumination.