Controlling the Structural Properties of Single Step, Dip Coated ZnO Seed Layers for Growing Perfectly Aligned Nanowire Arrays

Abstract

Mastering the structural ordering of ZnO seed layers by sol–gel process in terms of ultrathin thickness (i.e, <10 nm), strong c-axis texture, low mosaicity, low porosity, and low roughness is a critical challenge for the formation of well-ordered ZnO nanowires in solution. The effects of the solution concentration, of the withdrawal speed, and of the annealing process on the formation mechanisms of ZnO seed layers deposited by single dip process are revealed. The size and density of primary clusters in the sol are found to govern the evolution of the film thickness and nanoparticle average diameter through the solution concentration. The Landau–Levich theory modeling the dragging process accounts for the evolution of the film thickness only before annealing and over a reduced range of withdrawal speeds. The texture mechanisms along the c-axis are driven by particle/particle interactions during annealing and explained in the light of thermodynamic considerations. They are further determined locally by elec...