Specific electronic features have been found in structures consisting of metal oxide layers on silicon substrates upon swift heavy ion irradiation. These features are linked to the appearance of radiation-induced negative differential resistances in the structures. In the reversed bias direction they show high frequency current pulsations at around ∼10 kHz frequency. Their amplitude increases with increasing applied voltage. The pulsation frequency also shows a small increase. The current amplitude depends on the ion fluence and flux.