Effect of substrate temperature on sputtered indium-aluminum-zinc oxide films and thin film transistors

Indium-aluminum-zinc oxide (IAZO) films and thin film transistors (TFTs) were prepared at different substrate temperatures by RF magnetron sputtering. Both the unannealed and annealed IAZO films exhibited an amorphous state with very flat surface topographies. An increase in oxygen vacancies and a decrease in Hall mobility with the increase of substrate temperature were observed for the annealed IAZO films. The 25 degrees C-deposited film after annealing possessed the highest Hall mobility of 67.7 cm(2)/V. A slight increase in transmittance was observed after annealing with super-high average transmittances over 93.8% in the visible range and large optical bandgaps around 4.10 eV obtained for all the IAZO films. The IAZO TFT fabricated at 25 degrees C exhibited the best overall performance with the highest saturation mobility of 11.11 cm(2)/V, lowest subthreshold swing of 0.42 V/dec, lowest hysterisis of -0.31 V, and optimal threshold voltage of -5.12 V. (C) 2019 Elsevier B.V. All rights reserved.