Voltage Dependent Barrier Height, Ideality Factor and Surface States in Au/(NiS-PVP)/n-Si (MPS) type Schottky Barrier Diodes

Abstract

Metal-Polymer-Semiconductor (MPS) Schottky Barrier Diodes (SBD) were manufactured and their basic electrical parameters were obtained by the measurement of the forward and reverse bias current-voltage (I-V) in the wide bias voltage range (±3V) to determine the voltage dependent effects on Nickel-Sulphur (NiS) doped Poly Vinyl Pyrrolidone (PVP) polymer interlayer. The saturation current (I0), zero-bias barrier height (ΦB0), rectifying rate (RR), ideality factor (n) and the real value of series - shunt resistances (Rs - Rsh) were calculated. The voltage dependent profile of n (V), ΦB(V), and Rs (V) were derived. The forward bias ln I-V plot of the MPS type SBD indicates a good rectifier behaviour and it has two distinctive linear parts with different slopes which correspond to low (0.288 ≤V ≤0.625 V) and moderate (0.672 ≤ V ≤ 0.960 V) bias voltages and then deviates from linearity due to Rs and interlayer at high forward bias voltages. Energy dependent profile of Nss was obtained from the forward bias I-V data by considering voltage dependent barrier height (ΦB) and n. Nss plot represents U-shape behaviour in the forbidden bandgap. The mean value of Nss was found at about 7.0x1012 eV-1 cm-2 and this value is in the acceptable limit for a semiconductor device and such lower values of Nss are the consequences of the passivation effect on the surface states.