High-k-oxide/silicon interfaces characterized by capacitance frequency spectroscopy

Electron capture into insulator/silicon interface states is investigated for high-k dielectrics of Gd₂O₃ prepared by MBE and ALD, and for HfO₂ prepared by reactive sputtering, by measuring the frequency dependence of MOS capacitance. The capture cross sections are found to be thermally activated and to increase steeply with the energy depth of the interface electron states. The methodology adopted is considered useful for increasing the understanding of high-k-oxide/silicon interfaces.