Analysis of surface states and series resistance in Au/n-Si Schottky diodes with insulator layer using current-voltage and admittance-voltage characteristics

In order to good interpret the experimentally observed Au/n-Si (metal-semiconductor) Schottky diodes with thin insulator layer (18 angstrom) parameters such as the zero-bias barrier height (Phi(bo)), ideality factor (n), series resistance (R-s) and surface states have been investigated using current-voltage (I-V), capacitance-frequency (C-f) and conductance-frequency (G-f) techniques. The forward and reverse bias I-V characteristics of Au/n-Si (MS) Schottky diode were measured at room temperature. In addition, C-f and G-f characteristics were measured in the frequency range of 1 kHz-1 MHz. The higher values of C and G at low frequencies were attributed to the insulator layer and surface states. Under intermediate forward bias, the semi-logarithmic Ln (I)-V plot shows a good linear region. From this region, the slope and the intercept of this plot on the current axis allow to determine the ideality factor (n). the zero-barrier height (Phi(bo)) and the saturation current (I-s) evaluated to 2.878, 0.652 and 3.61 x 10(-7) A, respectively. The diode shows non-ideal I-V behavior with ideality factor greater than unity. This behavior can be attributed to the interfacial insulator layer, the surface states, series resistance and the formation barrier inhomogeneity at metal-semiconductor interface. From the C-f and G-f characteristics, the energy distribution of surface states (N-ss) and their relaxation time (tau) have been determined in the energy range of (E-c-0.493E(v))-(E-c-0.610) eV taking into account the forward bias I-V data. The values of N-ss and tau change from 9.35 x 10(13) eV(-1) cm(-2) to 2.73 x 10(13) eV(-1) cm(-2) and 1.75 x 10(-5) s to 4.50 x 10(-4) s, respectively. (C) 2009 Elsevier Ltd. All rights reserved.