Shallow electron traps in high-k insulating oxides

Abstract

In the present work the use of low temperature (77 K) charge injection and thermally activated emission is proposed as a universal method for characterization of shallow traps in high permittivity insulating oxides (HfO2, ZrO2, LaSiOx). A broad temperature range (77 K-300 K) allows one to evaluate density and energy distribution of electron traps within the energy depth range approximate to 1 eV below the oxide conduction band. The volume concentration of these traps is found to be in the range of 1019-1020 cm-3 in all studied materials indicating that shallow trapping will significantly affect performance of the high-k oxide-based devices operating at low temperature and/or very short pulse times.