Effects of annealing conditions on the dielectric properties of solution-processed Al₂O₃ layers for indium-zinc-tin-oxide thin-film transistors

In this paper, the effects of annealing conditions on the dielectric properties of solution-processed aluminum oxide (Al₂O₃) layers for indium-zinc-tin-oxide (IZTO) thin-film transistors (TFTs) have been investigated. The dielectric properties of Al₂O₃ layers such as leakage current density and dielectric strength were largely affected by their annealing conditions. In particular, oxygen partial pressure in rapid thermal annealing, and the temperature profile of hot plate annealing had profound effects on the dielectric properties. From a refractive index analysis, the enhanced dielectric properties of Al₂O₃ gate dielectrics can be attributed to higher film density depending on the annealing conditions. With the low-temperature-annealed Al₂O₃ gate dielectric at 350 °C, solution-processed IZTO TFTs with a field-effect mobility of ∼2.2 cm²/Vs were successfully fabricated.