Improved negative bias illumination instability of sol-gel gallium zinc tin oxide thin film transistors

We investigated the Ga doping effect on the performance and negative bias illumination instability of sol-gel zinc tin oxide (ZTO) thin film transistors (TFTs). The performance of the Ga doped ZTO (GZTO) TFTs is controlled and optimized by the concentration of Ga ions, which suppress the formation of oxygen vacancies. The negative bias illumination instability of the devices with a sol-gel hybrid material passivation layer is compared through a time-evolution stress analysis and illumination wavelength dependence measurements. The GZTO TFT exhibits improved stability relative to the ZTO TFT, because Ga ions effectively decrease charge trapping sites originating from oxygen vacancies.