Characteristics of Al-doped ZnO films annealed at various temperatures for InGaZnO-based thin-film transistors

• Fabrication of Al-doped zinc oxide (AZO) films by unbalanced magnetron sputtering
• Effects of annealing temperature on the properties of AZO thin films
• Improvement of electrical property with increasing annealing temperature
• Performance improvement of oxide thin film transistor with annealed AZO electrodes

Aluminum-doped ZnO (ZnO:Al, AZO) thin-films were deposited using a pulsed DC unbalanced magnetron sputtering system. The deposited AZO films were annealed in N2 ambient at various temperatures using a rapid thermal annealing equipment. The influence of the annealing temperature on the structural, electrical, and optical properties of the AZO films was experimentally investigated and the effect of the conductivity of the AZO source/drain (S/D) electrode on the device performance of an oxide-thin film transistor (TFT) was tested. Increasing the annealing temperature resulted in an improvement of the crystallinity of the films. Increasing grain size was found to lead to an increase in the conductivity of the AZO films. The a-IGZO TFTs fabricated with the annealed AZO S/D electrodes showed good performance. Consequently, the performance of the TFT was influenced by the conductivity of the AZO film, which was related to its structural properties.