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Nanorod postgrowth. Main idea : Conducting path formation by re-growth of ZnO nanorods (TFT channel). 2 nd growth. Randomly-deposited nanorods. Cold-welding between nanorods. Nanorod postgrowth. 1. Nanorod synthesis.
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Nanorodpostgrowth Main idea : Conducting path formation by re-growth of ZnOnanorods (TFT channel) 2nd growth Randomly-deposited nanorods Cold-welding between nanorods
Nanorodpostgrowth 1. Nanorod synthesis • Material: Hydrothermal-grown ZnO (Single-crystalline) • Method of Pacholski • Zn(Ac)2 0.8182g • 250μL water • 10mL methanol • 60ºC for 5hrs • Butylamine after synthesis • (Dispersion agent) • Nanorod specification • Single-crystalline (c-axis oriented) • Average width 10nm • 65nm-long
Nanorodpostgrowth • 2. Nanorod deposition • General spin-coating method • 2000rpm speed with 85mg/mL (highly concentrated) • Optimized for Full-covered and minimum multilayer • Self-assembled monolayer • Advantage: Perfect monolayer & coverage • Disadvantage: Additional transfer process
Nanorodpostgrowth 3. Nanorodpostgrowth • General hydrothermal growth method • Nanorod-deposited substrate is immersed in solution • SiO2 substrate: immune to ZnO nucleation • Zinc nitrate + HTMA • Water solvent • 90ºC for 1hr • 200ºC annealing for drying (15min) • Device fabrication with metal contact
Nanorodpostgrowth • 4. Points of experiment • Minimization of ligand: Ligand helps dispersion but detrimental for electric property • Postgrownnanorod size: Fully-covered deposition may be worse than partial-cover • (Postgrown size is shorter) • (Like fast nucleation -many nuclei- makes small grains) • Channel length effect: shorter channel – fewer grain boundary and better mobility • Nanorod orientation: oriented nanorods form low-angle boundary after postgrowth