Role of ZrO2 incorporation in the suppression of negative bias illumination-induced instability in Zn–Sn–O thin film transistors

Thin film transistors (TFTs) with In and Ga-free multicomponent Zn–Sn–Zr–O (ZTZO) channel layers were fabricated using the cosputtering approach. The incorporation of ZrO2 into the Zn–Sn–O (ZTO) films increased the contact resistance, which led to the degradation of the transport properties. In contrast, the threshold voltage shift under negative bias illumination stress (NBIS) was largely improved from −12.5 V (ZTO device) to −4.2 V (ZTZO device). This improvement was attributed to the reduction in the oxygen vacancy defects in the ZTZO film, suggesting that the photoinduced transition from VO to VO2+ was responsible for the NBIS-induced instability.