Colloidal ZnO quantum dot-based, solution-processed transparent field-effect transistors

Abstract

ZnO-based transistors were solution-processed using ∼3.6 nm sized ZnO quantum dots (QDs). Spin-deposited ZnO QD layer was annealed to remove QD capping organic molecules and to increase the connectivity of adjacent QDs. The resulting QD layer was highly transparent and crack free without any noticeable pores. 600 °C annealing of QD channel layer resulted in the highest electrical performances of bottom-gate QD-based transistors. A small quantity of Sn doping into the QD channel layer was found to be effective in further improving the electrical characteristics of the QD-based transistor, in particular exhibiting a higher field-effect mobility (0.282 cm 2 V −1 s −1 ) by more than 4 factors than that of an undoped QD-based one. Finally, a fully transparent Sn-doped QD-based device was demonstrated by sputter deposition of Ga-doped ZnO as source–drain transparent electrodes and its electrical properties were evaluated.