Flexible In-Ga-Zn-O thin-film transistors fabricated on polyimide substrates and mechanically induced instability under negative bias illumination stress

Flexible thin-film transistors (TFTs) incorporating In-Ga-Zn-O (IGZO) as the active layer were fabricated on polyimide substrates. The electrical properties and device stability were evaluated before and after detaching the polyimide from the carrier glass. The TFT performance and reliability under negative bias illumination stress (NBIS) degrade considerably once the polyimide film is separated from the rigid glass substrate. It is suggested that mechanical strain induces the formation of excess oxygen vacancies in the IGZO semiconductor, and these become ionized upon illumination to act as net positive charge traps during the NBIS measurements.