Highly efficient UV-Ozone treatment for IAZO active layer to facilitate the low temperature fabrication of high performance thin film transistors

We had found for the first time that short-time UV-ozone treatment can effectively regulate the electrical properties of sputtered InAlZnO (IAZO) films, and we successfully prepared high performance IAZO thin film transistors (TFTs) without thermal annealing. After the UV-ozone treatment, all IAZO films exhibited very flat surface topographies with small root mean square roughnesses (0.167-0.195 nm). With the increase of UV-ozone treatment time, the oxygen vacancies and consequently the carrier concentration of the films decreased monotonically, while the highest Hall mobility of 29.4 cm(2)/V was obtained for the 5 min-treated film. The IAZO TFT with 5 min UV-ozone treatment exhibited the best overall electrical properties with a high saturation mobility of 8.76 cm(2)/V, a high on-off current ratio of 6.44 x 10(8) and a low subthreshold swing of 0.73 V/dec. Meanwhile, it also displayed good negative bias illumination stability with a small shift of - 0.51 V observed in threshold voltage after the device being stressed for 3000 s.