A Strategy for High-Mobility and Highly-Stable Oxide TFTs

In this study, we show a reason why high-mobility oxide TFTs tends to exhibit poor reliability such as NBTS and PBTS. It is revealed that the NBTS mechanism is mainly attributed to the Fermi level shift of a-ITZO itself and it is highly dependent on the conduction band minimum location. Based on this background, we found that the charge transfer between ITZO active layer and CO-related impurities is responsible for NBTS instability. Consequently, we successfully developed a highly stable ITZO TFT with the mobility of 70 cm
²
/Vs by eliminating the CO-related impurities and the introduction of passivation layer.