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

Abstract

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 (V o 2+) in IGZO and hole trapping near the IGZO/Al2O3 interface via both V o 2+- and V o -mediated electron-hole pair creation. At lower λ, the devices under NBIS showed slower recovery characteristics, which were attributed to the stronger stabilization of V o 2+ near the IGZO/Al2O3 interface at RT.