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 (φ b ), series and shunt resistances (R s and R sh ), and the density of interface states/traps (N ss ) are strong functions of illumination level and applied bias voltage. The R s values were determined from the I-V characteristics, by using both Ohm's law. The energy distribution profile of N ss was also obtained from the forward bias I-V characteristics, by taking into account voltage dependent barrier height (φ e ) and ideality factor (n). It was found that Bi-doped PVA layer lead to a considerable decrease in the leakage current, R s and N ss and increase in R sh and rectifier rate (RR=I F /I R ). In conclusion, a thin Bi-doped PVA interfacial layer, considerably improved the diode performance, both in dark and under illumination.account voltage dependent barrier height (φ B (V)) and ideality factor n(V). Experimental results show that the Bi-doped interfacial PVA layer led to considerable decrease in the leakage current, R s and N ss and led to increase in R sh and rectifier rate (RR=I F /I R ). So, it can be said that Bi-doped PVA considerably improved the performance of SBD.
Experimental ProcedureFor the fabrication of Au/PVA (Bi-doped)/n-Si (MPS), (phosphor doped) single crystal silicon with surface orientation, 350 μm thickness and 0.7 Ω.cm resistivity was used. Si wafer was degreased in organic solution of peroxide-ammoniac solution in 10 minutes, and then etched in a sequence of H 2 O+HCl solution, and finally quenched in de-ionized water resistivity of 18 MΩ.cm for a prolonged time. Preceding each cleaning step, the wafer was rinsed thoroughly in de-ionized water. Immediately after surface cleaning, high purity (99.999%) gold (Au), with a thickness of ~2000Å, was thermally evaporated onto the whole back side of Si wafer, in a pressure about 10 -6 Torr in high vacuum metal evaporation system. In order to perform a low resistivity ohmic back metal contact, n-Si wafer was sintered at about 450°C for 5 min in N 2 atmosphere.Immediately after the formation of ohmic contact, 0.5 g of bismuth acetate was mixed with 50 g of polyvinyl Alcohol (PVA), molecular Citation: Alialy S, Tecimer H, Uslu H, Altındal Ş (2013) A Comparative Study on Electrical Characteristics of Au/N-Si Schottky Diodes, with and Without Bi-Doped PVA
