The interface states and series resistance effects on the forward and reverse bias I– V, C– V and G/ ω- V characteristics of Al–TiW–Pd 2Si/ n-Si Schottky barrier diodes

Abstract

Illumination intensity effects on the electrical characteristics of Al–TiW–Pd 2Si/ n-Si Schottky structures have been investigated in this study for the first time. The electrical parameters such as ideality factor ( n), zero-bias-barrier height ( Φ B0), series resistance ( R s), depletion layer width ( W D) and dopping concentration ( N D) of Al–TiW–Pd 2Si/ n-Si Schottky barrier diodes (SBDs) have been investigated by using the forward and reverse bias current–voltage ( I– V), capacitance–voltage ( C– V) and conductance–voltage ( G/ ω- V) measurements in dark and under illumination conditions at room temperature. The values of C and G/ ω increase with increasing illumination intensity due to the illumination induced electron–hole pairs in the depletion region. The density of interface states ( N ss) distribution profiles as a function of ( E c − E ss) was extracted from the forward I– V measurements by taking into account the bias dependence of the effective barrier heights ( Φ e) for device in dark and under various illumination intensities. The high values of N ss were responsible for the nonideal behavior of I– V, C– V and G/ ω characteristics. The values of R s obtained from Cheung and Nicollian methods decrease with increasing illumination intensity. The high values of n and R s have been attributed to the particular distribution of N ss, surface preparation, inhomogeneity of interfacial layer and barrier height at metal/semiconductor (M/S) interface. As a result, the characteristics of SBD are affected not only in N ss but also in R s, and these two parameters strongly influence the electrical parameters.