Synthesis and application of solution processed ZnO nanoparticles for thin-film transistors

Abstract

Solution-processed thin-film deposition methods can offer many advantages such as simplicity, low-cost, and high throughput that enable the fabrication of high-performance and low-cost electronics. In addition, Solution-processed deposition methods such as inkjet printing and imprinting, etc. offer the possibility of direct patterning of semiconductor thin films which could replace the conventional photolithographic technique. Therefore, solution-processed thin-film semiconductors can potentially enable low-cost thin-film transistor (TFT) manufacturing deposited/patterned using conventional low-cost solution technique. ZnO is a non-toxic inorganic semiconductor which potentially offers large electron channel mobility, excellent environmental stability and high transparency. So far, the main processed to deposit crystalline ZnO layers for TFTs include vacuum-based deposition and solution based deposition. Vacuum deposition methods generally achieve higher TFT characteristics, however are not likely to be low-cost manufacturing process. Until now, most sol-gel processed ZnO channel layers have been deposited using substrate heating or subjected to post-thermal annealing to increase the crystallinity of the ZnO layer. Our approach of the solution-processed ZnO thin-film semiconductors was through room temperature process of ZnO nanoparticle solutions with high-performance TFT characteristics. We synthesized size and shape controlled ZnO nanoparticles using sonochemical methods according to the molarity difference. All ZnO solutions were well dispersed in methanol without a dispersant reagent. Especially, ZnO nanorods showed highly crystallinity with the strong (100) peak from the X-ray diffraction (XRD) results. This implies excellent alignment of the nanorods along the substrate, in contrast with other aligned ZnO growth, where the ZnO nanorods are oriented perpendicularly to the surface of the substrate. The mobilities of ZnO TFTs using ZnO nanoparticle...