Electrical Properties of Indium Aluminum Zinc Oxide Thin Film Transistors

In this study, radio-frequency (RF) magnetron sputtering was used to deposit a 50 nm indium aluminum zinc oxide (IAZO) channel layer, following which a bottom-gate thin-film transistor (TFT) was fabricated. The oxygen ratio for the IAZO thin film was modulated from 0% to 6%. The film remained amorphous at annealing temperatures of 300°C and 500°C. Analysis of optical properties (performed via UV–Vis spectroscopy) shows that the bandgap increased from 5.24 eV to 5.32 eV when the oxygen flow ratio increased from 0% to 4%. The bandgap decreased to 5.19 eV when the flow ratio reached 6%. An appropriate variation of the O 2 /Ar flow ratio filled oxygen vacancies and improved the electrical properties; however, a higher oxygen ratio led to the regeneration of oxygen vacancies and degraded the device. TFTs with an oxygen flow ratio of 2% had a high mobility of 5.67 cm 2 /Vs, I on / I off 3.37 × 10 6 , and S.S. 0.61 V/dec.