A comparative study of the dielectric properties of Al/p-Si structures with 50 and 826 angstrom SiO2 interfacial layer

Abstract

Dielectric properties and ac electrical conductivity (σac) of Al/p-Si structures with 50 Ǻ (MIS) and 826 Ǻ (MOS) interfacial insulator layer (SiO2) have been investigated in the frequency range of 10 kHz-2 MHz using the capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements at room temperature. SiO2 layer was grown on p-Si by thermal oxidation method. Experimental results show that the dielectric constant (ε'), dielectric loss (ε''), loss tangent (tanδ), ac electrical conductivity (σac) and the real and imaginary parts of electric modulus (M' and M'') are strong functions of frequency in depletion region. Accordingly, it has been found that as the frequency increases, ε' values decrease while an increase is observed in σac and the electric modulus for two samples. On the other hand, the values of ε'' and tanδ decrease with the increasing frequency for MIS and MOS structures at low frequencies while, at high frequencies, the values of ε'' and tanδ increase with the increasing frequency for two structures. As a result, the interfacial polarization can more easily occur at low frequencies and/or the number of interface states (Nss) localized at SiO2/Si interface, consequently contributed to the improvement of dielectric properties and ac electrical conductivity of these structures.