Vibronic nature of hafnium oxide/silicon interface states investigated by capacitance frequency spectroscopy

Using a method based on the frequency dependence of capacitance, cross sections for electron capture into energy states at the interlayer/silicon interface have been investigated for HfO2 that is deposited on silicon by reactive sputtering. We find that the capture cross sections are thermally activated and steeply increase with increasing energy depth. Both features can be attributed to the same physical origin, indicating vibronic trap properties, where the capture mechanism is governed by multiphonon processes.