Electrical Properties of Indium Aluminum Zinc Oxide Thin Film Transistors

In this study, radio-frequency (RF) magnetron sputtering was used to deposit a 50nm 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 degrees C and 500 degrees C. Analysis of optical properties (performed via UV-Vis spectroscopy) shows that the bandgap increased from 5.24eV to 5.32eV when the oxygen flow ratio increased from 0% to 4%. The bandgap decreased to 5.19eV 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 5.67cm(2)/Vs, I-on/I-off 3.37x10(6), and S.S. 0.61V/dec.