Electrical properties of Ba0.8Sr0.2TiO3 thin film with NTC effect [thin film resistor]

Ba_0.8Sr_0.2TiO₃ thin films, deposited on a SiO₂/Si substrate by an argon ion-beam sputtering technique, are used to fabricate thin-film resistors by standard integrated-circuit technology. The resistance-temperature characteristics of the thin-film resistor show that the thin-film resistor has good thermal sensitivity with negative temperature coefficient from room temperature to 200°C (-5.3%°C^-1 at 30°C for a test voltage of 6 V) as opposed to the positive temperature coefficient of the same material in sintered ceramic form. The current-voltage characteristics reveal that in the low-voltage region,. thermionic emission is dominant, while in the high-voltage range, a space-charge limited conduction mechanism plays a major role. In the medium-voltage range, there is the normal ohmic behavior. The effects of frequency on the impedance of the thin-film resistor at various temperatures are also investigated.