Frequency and voltage effects on the dielectric properties and electrical conductivity of Al-TiW-Pd2Si/n-Si structures

Different from conventional metal-Si compounds-n-Si structures, the thin film of TiW alloy was deposited on Pd2Si-n-Si to form a diffusion barrier between aluminum (Al) and Pd2Si-n-Si. Dielectric properties and electrical conductivity of TiW-Pd2Si/n-Si structures in the frequency range of 5kHz-10MHz and voltage range of (-4V) to (10V) have been investigated in detail by using experimental C-V and G-V measurements. Experimental results indicate that the values of epsilon'show a steep decrease with increasing frequency for each voltage. On the other hand, the values of epsilon''show a peak, and its intensity increases with decreasing voltage and shifts towards the lower frequency side. The ac electrical conductivity (sigmaac) and the real part of electric modulus (M') increase with increasing frequency. Also, the imaginary part of electric modulus (M'') shows a peak and the peak position shifts to higher frequency with increasing applied voltage. It can be concluded that the interfacial polarization can be more easily occurred at low frequencies, and the majority of interface states at metal semiconductor interface, consequently contributes to deviation of dielectric properties of TiW-Pd2Si/n-Si structures.