Effect of the annealing ambient on the electrical characteristics of the amorphous InGaZnO thin film transistors

The in?uence of the thermal annealing on the amorphous indium gallium zinc oxide (a-IGZO) thin-?lm transistors (TFTs) under different ambient gases has been systematically addressed. The chemical bonding states and transfer characteristics of a-IGZO TFTs show evident dependence on the annealing ambient gas. For the a-IGZO TFTs in the oxygen ambient annealing at 250 °C for 30 mins exhibited a maximum ?eld effect mobility (max μFE) of 9.36 cm ²/V ̇ s, on/off current ratio of 6.12 × 10 ¹⁰, and a subthreshold slope (SS) of 0.21 V/decade. Respectively, the as-deposited ones without annealing possess a max μFE of 6.61 cm ²/V ̇ s, on/off current ratio of 4.58 × 10 ⁸, and a SS of 0.46 V/decade. In contrast, the a-IGZO TFTs annealed at 250 °C for 30 mins in the nitrogen ambient would be degraded to have a max μ FE of 0.18 cm ²/V ̇ s, on/off current ratio of 2.22 × 10 ⁴, and a SS of 7.37 V/decade, corresponding. It is attributed to the content of the oxygen vacancies, according the x-ray photoelectron spectroscopy (XPS) analyze of the three different samples.