Improved bias stability and UV photoresponse in oxide thin-film transistors with titanium-doped InZnSnO channels

Indium zinc tin oxide (IZTO) has emerged as a promising alternative for thin-film transistor (TFT) channels, owing to its high electron mobility, yet it suffers from oxygen vacancies (V_O)-induced negative bias illumination stress (NBIS) instability and slow photocarrier recovery. In this work, we propose titanium (Ti)-doped IZTO (IZTTO) to simultaneously improve bias stability and UV photoresponse. Ti-doped devices exhibit significantly suppressed threshold voltage shifts under NBIS, attributed to V_O passivation and Ti⁴⁺-induced sub-bandgap states that capture photogenerated electrons. Moreover, IZTTO TFTs show enhanced UV photoresponse with a high photo-to-dark current ratio (PDCR) and steep pulse edges, especially at 10% Ti doping. Controlled Ti doping thus enables simultaneous improvement in bias stability and UV sensitivity, offering a viable material strategy for high-performance oxide TFTs in displays and UV detection.