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 molecular beam epitaxy (MBE) and atomic layer deposition (ALD), and for HfO₂ prepared by reactive sputtering, by measuring the frequency dependence of Metal Oxide Semiconductor (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.