Mobility Enhancement and OFF Current Suppression in Atomic-Layer-Deposited ZnO Thin-Film Transistors by Post Annealing in O2
The impacts of postdeposition annealing in O<sub>2</sub> on the electrical performance of atomic-layer-deposited ZnO thin-film transistors (TFTs) have been investigated. The TFTs are fabricated on transparent quartz substrates with Al<sub>2</sub>O<sub>3</sub> dielectrics, ZnO active layers, and Cr/Au electrodes. The best field-effect mobility of 21.3 cm<sup>2</sup>/Vs and a large ON/OFF current ratio of 10<sup>7</sup> are obtained under 400°C annealing treatment in O<sub>2</sub>. Furthermore, analysis indicates that reduction of OH bonds in both ZnO and Al<sub>2</sub>O<sub>3</sub> layers is the key issue to achieve the excellent properties.