IZO transistors with Al₂O₃ as gate dielectrics have been investigated. To improve permittivity in an ambient dielectric layer, we grew Al₂O₃ by atomic layer deposition directly onto the substrates. Then, we prepared IZO semiconductor solutions with 0.1 M indium nitrate hydrate [In(NO₃)₃·xH₂O] and 0.1 M zinc acetate dehydrate [Zn(CH₃COO)₂·2H₂O] as precursor solutions; the IZO solution made with a molar ratio of 7:3 was then prepared. It has been found that these oxide transistors exhibit low operating voltage, good turn-on voltage, and an average field-effect mobility of 0.90 ㎠/Vs in ambient conditions. Studies of low-voltage driving of IZO transistors with atomic layer-deposited high-k Al₂O₃ as gate dielectric provide data of relevance for the potential use of these materials and this technology in transparent display devices and displays.