Single step formation of indium and tin doped ZnO nanowires by thermal oxidation of indium–zinc and tin–zinc metal films: Growth and optical properties

Abstract

Single step transformation of indium–zinc and tin–zinc films into doped ZnO nanowires is demonstrated. In and Sn doped ZnO nanowires are formed by the annealing of In–Zn and Sn–Zn bilayer films to 500°C in air. The nanowires of 15–100nm diameter and lengths up to 2µm are formed by the self-catalysis mechanism. Thus, by a single step annealing process doped ZnO nanowires can be realized. Independent of processing conditions all the nanostructures are polycrystalline as evidenced from x-ray diffraction patterns. The optical transmission, reflectance and absorption, in the wavelength range between 200 and 2500nm, have been measured as a function of annealing temperature. It is shown that all the bilayers and the In and Sn doped nanowires can be used as solar absorber materials due to their high absorption, low transmittance and reflectance, in this region of the spectrum. In certain cases, the nanowires exhibit high transmittance and very low reflectance making them very attractive for use as anti-reflection coatings.