Influence of the thermal annealing temperature of the channel layers grown at room temperature on the device performance in the ZnO thin-film-transistors

This study examined the effect of thermal annealing of the channel layers on the device performance of ZnO thin-film-transistors (TFTs). Thermal annealing of the ZnO channel layers grown by sputtering was performed at various temperatures under a nitrogen atmosphere. The electrical resistivity of the ZnO layers decreased with increasing annealing temperature due to the formation of oxygen vacancies, and showed no hard saturation in the TFT devices thermal-annealed at higher temperatures. The thermal treatment of the channel layer at 350 °C caused an increase in field-effect mobility compared to those of the TFT with the as-grown channel layer. In addition, the thermal-annealed TFT showed high stability in the threshold voltage variations with ΔV of <2.1 V. The results suggest that thermal annealing of the ZnO channel layer at an appropriate temperature is a significant factor for improving the device performance.