Base-etch removal of a ligand shell in thin films of ZnO nanoparticles for electronic applications

Abstract

Functionalized nanoparticles offer many advantages regarding homogenous film formation. However, to utilize the semiconductive properties of metal oxides the insulating species on the particle's surface need to be removed. A widely employed route is the thermal decomposition of the ligands. If one wishes to lower the process temperature it is necessary to find alternative procedures. The organic nature of the ligand shell of octylamine-functionalized ZnO nanoparticles is a contrast to the properties of the inorganic metal oxide. This discrepancy is used to aid the ligand removal by potassium hydroxide etching. Wet etching processes are widespread in the semiconductor industry. We report on the beneficial effect of a mild base treatment on the electrical properties of ZnO-based thin-film transistors. The annealing temperatures can be drastically reduced; a field effect mobility value of 0.1 cm² V⁻¹ s⁻¹ was obtained at a maximum process temperature of 350 °C.