Refined analysis of C–V and I–V characteristics of Al/dielectric/Si structures containing nanosized Ta₂O₅/SiO_xN_y dielectric stack

Abstract

In this work we carry out a refined analysis of the C–V and I–V characteristics of Al/Ta2O5/SiOxNy/Si structures at limited voltages (from −3.0 V to +1.0 V). The modified Terman method was used to determine the interface state densities over the silicon bandgap, and an extended comprehensive model was utilised to determine the I–V characteristics of metal/high-κ/SiO2/Si structures. A sharp peak in interface states distribution is observed at around 0.1 eV above the valence band top; its presence is identified as the origin of the double-knee shaped C–V characteristics. The substantial contribution of the Schottky effect was observed in the leakage currents at low voltages.