Electrical Instability of Amorphous-Indium-Gallium-Zinc-Oxide Thin-Film Transistors under Ultraviolet Illumination**Supported by the Key Industrial R&D Program of Jiangsu Province under Grand No BE2015155, the Priority Academic Program Development of Jiangsu Higher Education Institutions, and the Fundamental Research Funds for the Central Universities under Grant No 021014380033.

Abstract

The electrical instability behaviors of amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) under ultraviolet (UV) illumination are studied. As UV radiation dosage increases, the turn-on voltage of the TFT shows continuous negative shift, which is accompanied by enhanced degradation of sub-threshold swing and field-effect mobility. The electrical instability is caused by the increased carrier concentration and defect states within the device channel, which can be further attributed to additional oxygen vacancy generation and ionization of oxygen vacancy related defects upon UV illumination, respectively. Furthermore, the performance of the a-IGZO TFT treated with UV radiation can gradually recover to its initial state after long-time storage.