Solution-based surface modification method for high-performance ZnO transistors

Abstract

A solution-based surface modification method is first proposed for improving electrical performance of the ZnO transistors. The ZnO transistors are infiltrated for treatment in the 0.01 mol/L NH4Cl solution, and the effects of treatment time on electrical properties are examined. We find that turn-on voltage (VON) positively correlates with the treatment time, consequently sub-threshold swing (SS) is optimized significantly. After treatment for 30 s, the device showed a shift of VON from −1.96 V to −1.24 V. Additionally, the SS decreased from 154.5 mV/dec to 104.4 mV/dec, and the μFE increased from 20.69 cm2/V·s to 25.55 cm2/V·s. The XPS results imply that the surface modification method effectively reduces oxygen vacancies of the ZnO active layer, which achieves the target of adjusting VON and SS. Besides, characterization results show that the surface is smoother and the wettability is enhanced after treatment. This solution-modified strategy is expected to be put into practical application due to the advantages of easy operation, low cost, low-temperature environmental protection, and capable of large-scale treatment.