Negative differential resistance (NDR) switching was observed in ZnMg Ocrystalline thin films grown on the p type Si with a thin native SiO oxide layer by ultrasonic spray pyrolysis (USP). The NDR switching was observed during the RESET cycle. This effect is explainedи by the resonant tunneling of electrons through the Ag nanoclusters in SiO2layer after rupture of conductive silver filaments.