Improvement in the bias stability of zinc oxide thin-film transistors using Si3N4 insulator with SiO2 interlayer

The performance of ZnO thin film transistors (TFT) subjected to SiO2 interlayer treatments on Si3N4 insulators was investigated. In the case of a SiO2 interlayer of 10 nm on Si3N4 insulator, a drastic improvement in device performance was obtained. ZnO TFT with this interlayer showed reduced trap density between the Si3N4 and ZnO channel, bringing remarkable improvement in bias stability characteristics. These devices show good performance and exhibit a high field-effect mobility of 6.41 cm2/Vs, an on/off current ratio of 108, and a subthreshold swing of 1.46 V/decade. Also, the turn-on voltage shifted from − 2 V to − 6 V with negligible changes in the subthreshold swing and field effect mobility after total stress time.