Recovery characteristics of solution-processed ZTO thin-film transistors

We investigated the negative-bias illumination stress (NBIS) and the recovery characteristics of solution-processed amorphous zinc-tin-oxide (ZTO)-based thin-film transistors (TFTs). We developed TFTs with a bottom gate structure that used SiO 2 films for the gate insulator. The developed TFTs were under NBIS in air at room temperature (RT) with a gate-to-source voltage of −10 V and a white-light power density of 6.2 mW/cm 2 . For the devices under NBIS, the NBIS-induced instability is attributed to the combined effects of 1) the creation of a low density of subgap states such as ionized oxygen vacancies ( V o 2+ ) near the Fermi level in ZTO, 2) a fast and large increase in the photo-conductivity at the off-state due to photo-induced band-to-band electron-hole pair generation, and 3) the hole trapping near the ZTO/SiO 2 interface. The devices under NBIS also exhibit fast exponential recovery characteristics at RT, which are attributed dominantly to detrapping of holes near the ZTO/SiO 2 interface and partially to the weak stabilization of V o 2+ near the interface.