Improvement in the bias stability of zinc oxide thin-film transistors using Si3N4 insulator with SiO_2 interlayer

摘要

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.