Mobility Enhancement and OFF Current Suppression in Atomic-Layer-Deposited ZnO Thin-Film Transistors by Post Annealing in O2

Abstract

The impacts of postdeposition annealing in O2 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 $\mathrm{cm}^{2}$ /Vs and a large ON/OFF current ratio of $10^{7}$ are obtained under 400 °C annealing treatment in O2. Furthermore, analysis indicates that reduction of OH bonds in both ZnO and Al2O3 layers is the key issue to achieve the excellent properties.