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-2 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 Al2O3 dielectrics, ZnO active layers, and Cr/Au electrodes. The best field-effect mobility of 21.3 cm(2)/Vs and a large ON/OFF current ratio of 10(7) are obtained under 400 degrees C annealing treatment in O-2. Furthermore, analysis indicates that reduction of OH bonds in both ZnO and Al2O3 layers is the key issue to achieve the excellent properties.