The effect of UV treatment on the recovery characteristics of a-IGZO-based thin film transistors

We investigated the effects of ultraviolet (UV) treatment on the negative bias illumination stress (NBIS) and the recovery characteristics of amorphous indium-gallium-zinc-oxide (a-IGZO)-based transparent thin-film transistors (TTFTs). We developed TTFTs with a top gate structure that used a-IGZO and Al2O3 films for the active layer and the gate dielectric, respectively. The developed TTFTs were under NBIS in air at room temperature (RT) at wavelengths of 190 - 517 nm. For the devices with NBIS that had been treated with visible light (wavelength (λ) < 414 nm), the NBIS-induced instability is attributed to the combined effects of subgap-assisted electron generation via ionized oxygen vacancies (Vo2+) in IGZO and hole trapping near the IGZO/Al2O3 interface via both Vo2+ - and Vo-mediated electron-hole pair creation. At lower λ, the devices under NBIS showed slower recovery characteristics, which were attributed to the stronger stabilization of Vo2+ near the IGZO/Al2O3 interface at RT.