Oxide thin-film transistor for flexible display applications

Flexible thin-film transistors (TFTs) incorporating In-Ga-Zn-O (IGZO) as the active layer were fabricated on polyemide (PI) substrates, which were detached from the carrier glass after TFT fabrication. The application of appropriate buffer layer and mechanical strain affected the TFT performance and stability. The adoption of the SiNx/AlOx buffer layer as water and hydrogen diffusion barriers significantly improved the devices performance and stability compared to single SiNx or SiOx buffer layers. The TFT performance and reliability under negative bias illumination stress (NBIS) degrade considerably in once the PI film is detached from glass substrate. It is suggested that mechanical strain induces the formation of excess oxygen vacancies in the IGZO film, and these become ionized upon illumination to act as net positive charge traps.