Device properties of ZnO nanoparticle-based semiconductor oxide TFTs and applications

S. Chul Lim, J.Y. Oh, J.B. Koo, C.W. Park, S-W Jung, B.S. Na
Electronics and Telecommunications Research Institute (ETRI), KR

Keywords: ZnO TFTs, solution process, nanoparticle

Summary:

ZnO nanoparticles were synthesized using a facile sonochemical method with modification of previously conditions. Firstly, zinc acetate dehydrate [Zn(CH3COO)2∙2H2O] and potassium hydroxide [KOH] were dissolved into methanol. The reaction mixture was sonicated for one hour. Currently the utmost challenge in the field is to gain a most complete understanding of the interplay between the parameters synthesis, processing and semiconductor performance for future development of printable electronic devices based on inorganic semiconductors such as ZnO. This work showed that the ink-jet printing technique was a convenient and low cost method to prepare films with controlled film thickness. TFT devices were fabricated in the bottom contact geometry. The ZnO active channel layer was patterned with drops using a piezo ink-jet device. For film synthesis, inkjet printed ZnO was annealed at 150 oC for 30 min in air. The TFTs device has a channel width(W) of 100 µm and a channel length(L) of 10µm. The carrier charge mobility was determined to be 0.162cm2 V-1s-1 with FET threshold voltage of -4 V and on/off current ratio 10^4. It was demonstrated that the solution-based ZnO nanoparticle active layer allowed the production of high performance TFTs for low-cost, large area electronics and flexible devices.