Improvement in the bias stability of zinc oxide thin-film transistors using Si 3N 4 insulator with SiO 2 interlayer

Abstract

The performance of ZnO thin film transistors (TFT) subjected to SiO 2 interlayer treatments on Si 3N 4 insulators was investigated. In the case of a SiO 2 interlayer of 10 nm on Si 3N 4 insulator, a drastic improvement in device performance was obtained. ZnO TFT with this interlayer showed reduced trap density between the Si 3N 4 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 cm 2/Vs, an on/off current ratio of 10 8, 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.