Limitations in the methods of determination of conduction mechanisms in high-permittivity dielectric nano-layers

The standard methods of determination of the dominant conduction mechanisms in high-permittivity dielectrics were discussed for the case of very thin films. The outcomes from the estimation method were tested on the theoretical results obtained by the use of a comprehensive model describing the I–V characteristics of Ta2O5/SiO2 stacked layers. It is shown that the standard method based on the determination of a slope in Poole–Frenkel plot provides only a rough estimation that may lead in some cases to essentially incorrect results. The observed disagreement is explained by the modifications induced by the presence of an unavoidably grown SiO2-like few nanometers thick interfacial layer.