title: Investigation of Nucleation Mechanism and Tapering Observed in ZnO Nanowire Growth by Carbothermal Reduction Technique.
abstract: ZnO nanowire nucleation mechanism and initial stages of nanowire growth using the carbothermal reduction technique are studied confirming the involvement of the catalyst at the tip in the growth process. Role of the Au catalyst is further confirmed when the tapering observed in the nanowires can be explained by the change in the shape of the catalyst causing a variation of the contact area at the liquid-solid interface of the nanowires. The rate of decrease in nanowire diameter with length on the average is found to be 0.36 nm/s and this rate is larger near the base. Variation in the ZnO nanowire diameter with length is further explained on the basis of the rate at which Zn atoms are supplied as well as the droplet stability at the high flow rates and temperature. Further, saw-tooth faceting is noticed in tapered nanowires, and the formation is analyzed crystallographically.
authors: Electrical and Computer Engineering Department, University of Illinois, Chicago, IL, 60607, USA. akar2@uic.edu.
authors: Ayan
authors: A
authors: Kar
authors: Research Resources Center, University of Illinois, Chicago, IL, 60607, USA.
authors: Ke-Bin
authors: KB
authors: Low
authors: Center for Nanotechnology, NASA Ames Research Center, Moffett Field, CA, 94035, USA.
authors: Michael
authors: M
authors: Oye
authors: Electrical and Computer Engineering Department, University of Illinois, Chicago, IL, 60607, USA.|Department of Physics, University of Illinois, Chicago, IL, 60607, USA.|Department of Bioengineering, University of Illinois, Chicago, IL, 60607, USA.
authors: Michael A
authors: MA
authors: Stroscio
authors: Electrical and Computer Engineering Department, University of Illinois, Chicago, IL, 60607, USA.|Department of Physics, University of Illinois, Chicago, IL, 60607, USA.
authors: Mitra
authors: M
authors: Dutta
authors: Research Resources Center, University of Illinois, Chicago, IL, 60607, USA.
authors: Alan
authors: A
authors: Nicholls
authors: Center for Nanotechnology, NASA Ames Research Center, Moffett Field, CA, 94035, USA.
authors: M
authors: M
authors: Meyyappan
keywords: Microscopy; Nanowires; ZnO