Annealing Treatment on Amorphous InAlZnO Films for Thin-Film Transistors

Amorphous InAlZnO (a-IAZO) films were grown by pulsed laser deposition at room temperature and annealed at various temperatures. The amorphous state of a-IAZO films is thermally stable at high temperatures up to 700 degrees C. The films exhibit a high visible transmittance above 95% and an appropriate resistivity on the order of 10(6) Omega.cm. As the annealing temperature increases, the optical bandgap and resistivity decrease in general. The microcracks form in films at an annealing temperature above 500 degrees C. The a-IAZO films annealed at 400 degrees C are suitable for channel layers of thin-film transistors (TFTs) and the devices demonstrate good performances with an on/off ratio of 10(8) and field-effect mobility of 2.2 cm2.V-1.s(-1). The observations will provide useful physical insight into film properties and also offer basic design guideline for a-IAZO TFTs.