No abstract

An all-sputtered oxide TFT process combined with simultaneous ultraviolet and thermal (SUT) treatment for consecutive fabrication processes at low temperatures.

W-doped InZnO (WIZO) thin-film transistors (TFTs) were fabricated by co-sputtering with different W doping concentrations. We varied the W doping concentration to change the device performance and stability of the WIZO TFTs. WIZO TFTs with a W doping concentration of ∼1.1% showed the lowest threshold voltage shift and hysteresis. We correlated the device characteristics with the evolution of the electronic structure, such as band alignment, chemical bonding states, and band edge states. As the W doping concentration increased, the oxygen-deficient bonding states and W suboxidation states decreased, while the conduction-band offset and the incorporation of the WO x electronic structure into the conduction band increased.

This study suggests a sequential ambient annealing process as an excellent post-treatment method to enhance the device performance and stability of W (tungsten) doped InZnO thin film transistors (WIZO-TFTs). Sequential ambient annealing at 250 °C significantly enhanced the device performance and stability of WIZO-TFTs, compared with other post-treatment methods, such as air ambient annealing and vacuum ambient annealing at 250 °C. To understand the enhanced device performance and stability of WIZO-TFT with sequential ambient annealing, we investigate the correlations between device performance and stability and electronic structures, such as band alignment, a feature of the conduction band, and band edge states below the conduction band. The enhanced performance of WIZO-TFTs with sequential ambient annealing is related to the modification of the electronic structure. In addition, the dominant mechanism responsible for the enhanced device performance and stability of WIZO-TFTs is considered to be a change in the shallow-level and deep-level band edge states below the conduction band.

The effects of the neutron irradiation treatment on indium-gallium-zinc oxide (IGZO) are investigated as a function of the neutron irradiation time. With an increase in neutron irradiation time, the oxygen vacancies associated the oxygen deficient states increase, and both shallow and deep band edge states below the conduction band also increase. Moreover, the conduction band offset continuously decreases because of the increase in the oxygen vacancies with increasing the neutron irradiation time. In IGZO TFTs with the neutron irradiation time for 10 s, superior device performance demonstrates such as the lower threshold voltage, higher field effect mobility, smaller sub-threshold gate swing, larger on-off current ratio, and improved bias stability, comparing those of other IGZO TFTs.