High On/Off ratio and robust photo-stability by interstitial composition in a-IGTO/TiO_x TFT

We present a significant breakthrough in the development of amorphous oxide semiconductor (AOS)-based thin-film transistors (TFTs), with particular emphasis on their potential for flexible and transparent electronic applications. Our work addresses the challenge of creating high-performance TFTs on flexible substrates, which require low-temperature processing owing to their material properties. By focusing on amorphous indium–gallium–tin oxide (a-IGTO) and leveraging the unique Ti–O bonding characteristics during sputtering, we successfully induced interstitial composition between a-IGTO and Titanium oxide (TiO_x). This interaction generated oxygen vacancies that greatly improved the electrical performance of the ultra-thin AOS TFTs. Our results show that incorporating TiO_x into a-IGTO during low-temperature fabrication leads to a substantial increase in electron concentration, resulting in over a 30-fold increase in mobility and more than a 50-fold improvement in on-current. Moreover, the controlled formation of vacancy traps was crucial for enhancing the illumination stability, as evidenced by in the reduced threshold voltage shifts and improved I_on/I_off ratios under different illumination stresses. By addressing the inherent trade-off between the high-temperature annealing typically required for optimal TFT performance and the low-temperature processing essential for flexible substrates, the present study offers a promising strategy for producing high-performance AOS-based TFTs.