International audienceZnO nanowires grown in liquid phase are considered as promising building blocks for a wide variety of optical and electrical devices. However, their structural morphology is still limited by the lack of understanding of their growth mechanisms. We have systematically investigated the effects of orientation and polarity of ZnO monocrystals acting as substrates on the formation mechanisms of ZnO by chemical bath deposition. Under identical growth conditions, two-dimensional layers develop on nonpolar m- and a-plane ZnO monocrystals. In contrast, nanowires form on O-polar c-plane ZnO monocrystals, while more complex nanostructures including nanowires grow on Zn-polar c-plane ZnO monocrystals. All of the structures have homoepitaxially nucleated. Very specifically to chemical bath deposition, both O- and Zn-polar c-planes are found to be active, and no polarity inversion domain boundary is observed on O-polar c-plane ZnO monocrystals, allowing the growth of O-polar ZnO nanowires. These findings reveal the crucial role of crystal orientation and polarity in the growth of ZnO nanowires in liquid phase similarly to their growth in vapor phase. They further cast a new light on the general understanding of the growth of ZnO nanowires and enable the revisiting of their formation mechanisms in liquid phase on seed layers consisting of ZnO nanoparticles

International audienceMastering 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 electron backscattered diffraction. Importantly, an alternative annealing process under argon flux is specifically developed for sol–gel process and is shown to form remarkably well-textured, compact ZnO seed layers with a very low mosaicity and porosity as well as a thin thickness as small as 10 nm. These ZnO seed layers lead to the growth of well-ordered ZnO nanowires by chemical bath deposition with a remarkable mean tilt angle smaller than 6° as deduced by X-ray pole figures. These findings represent a significant step toward the more efficient integration of ZnO seed layers grown by sol–gel process into ZnO nanowire-based devices