Influence of ammonia, lithium hydroxide, and hexamine on ZnO films synthesized by successive ionic layer adsorption and reaction technique

摘要

Various nanostructured zinc oxide (ZnO) films have been developed on non-seeded soda-lime glass substrates by successive ionic layer adsorption and reaction (SILAR) method, employing different baths of aqueous zinc sulfate solution using complexing agents of ammonia, lithium hydroxide, and hexamine. Influence of complexing agents on the structural, morphological, chemical compositional, optical and electrical properties of the films were investigated and compared among and with the samples annealed at 400 C. Role of complexing agents on the growth process was discussed. X-ray diffraction analysis revealed that the ZnO films were polycrystalline dominating with (100), (002), and (101) oriented crystallites of hexagonal wurtzite structure. The lattice constants, c/a ratio, internal relaxation parameter, anion-cation (Zn-O) bond length, and the tetrahedral angles of ZnO films were determined. Cauliflower, flower, and flower-like nanorod morphologies of the films from the respective baths were exposed by scanning electron microscopic studies. Optical analysis of all films except that prepared from hexamine showed low absorbance and a higher transmittance 70-85 % in the entire visible region. Resistivity of annealed films was one order of magnitude lower than that of the as-grown films. We demonstrated utility of SILAR as an efficient single step soft chemical route for obtaining high-quality crystalline ZnO films having high-specific surface area on non-seeded substrates.