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

Ba0.8Sr0.2TiO3 thin films deposited on a SiO2/Si substrate by 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 degrees C (-5.3 %degrees C-1 at 30 degrees 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(ye characteristics reveal that in the low-voltage region, thermionic emission is dominant, while in the high-voltage range, 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.