Correlation between interface state properties and electron transport at ultrathin insulator/Si interfaces

interface state properties and tunnel transport properties of ultrathin ins ulators formed on Si surfaces at low temperatures (LT) were characterized b y XPS, contactless UHV C-V and I-V methods. Electron cyclotron resonance (E CR)-assisted N2O plasma process realized the formation of good interface wi th low interface state density. On the other hand, strong Fermi level pinni ng was observed at the interfaces formed by chemical oxidation and LT therm al oxidation, due to high density of interface states. In these interfaces, there was a large discrepancy between the measured tunnel I-V curves and t he calculated ones using the direct tunnel theory. This discrepancy was exp lained in terms of the large band bending due to the high density of interf ace states, which causes depletion of electrons at the interface. (C) 2000 Elsevier Science B.V. All rights reserved.