Rectifying Properties of Oxide Semiconductor Heterostack Films at Elevated Temperatures

Heterostack films of p-type NiO and n-type TiO₂ semiconductors were deposited by a method of chemical solution deposition on a glass substrate having a sputtered ITO (In₂O₃ doped with Sn) electrode. Transparent films with total thickness of about 280 nm were obtained by heat treatments at 600°C. NiO reacted with TiO₂ to give a NiTiO₃ thin layer between them. The films exhibited a typical rectifying I-V behavior and this property was maintained at 300°C. The thickness of the NiTiO₃ intermediate layer increase with the heating time at 600°C and leading to a decrease of the current density at low voltage.