Multifunctional zinc oxide nanostructures for a new generation of devices

ZnO is a natural n-type widespread semiconductor with wide direct bandgap of 3.37 eV, large exciton bending energy (60 meV) and high optical gain (300 cm−1). One dimensional ZnO nanomaterials such as nanowires or nanorods have focused much attention due to their multifunctionality in optoelectronic devices, gas sensing, piezoelectricity and thin film transistors for transparent and flexible electronics. Solution-phase chemical synthesis of nanomaterials has several important advantages, as low temperatures, high versatility, low cost, simple equipments and handling. The paper presents the chemical bath deposition synthesis and characterization of ZnO 1D nanostructures grown on glass substrates seeded with gold layer, pre-prepared ZnO nanoparticles or sol–gel derived ZnO layer. The obtained ZnO nanowires/nanorods were structurally and morphologically characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and the growth mechanism is discussed. The seed layer significantly affects the surface distribution and orientation of the grown 1D nanostructures. The diameter of the nanowires is mainly controlled by the concentration and temperature of the growth solution. The effect of growth conditions on the surface chemical composition and surface states/defects of semiconducting 1D nanostructures was investigated using X-ray photoelectron spectroscopy. The optical and electrical properties are presented.