Synthesis, characterization and thermal decomposition study of zinc propionate as a precursor for ZnO nano-powders and thin films

摘要

A simple, low-temperature and low cost water-based chemical solution method for the preparation of ZnO nano-powders and thin films is presented. A stable, clear and environmentally friendly precursor solution was obtained by the reaction of zinc acetate dihydrate, Zn(CH_3COO)_2 2H_2O with an excess of propionic acid, CH)CH_2COOH and the further addition of ammonia, NHj. The thermal decomposition process of the powdered solution was studied by TG/DTA analysis in air and in humid oxygen atmosphere coupled with a quadrupole mass spectrometer (QMS). The precursor solution was spin-coated on single-crystalline Si( 1 1 1) substrates and thermally treated at 400 ℃ for 2 h in air in order to obtain ZnO thin films. The X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) investigations indicated that the synthesized ZnO nano-powders and thin films present a pure wurtzite structure. The morphology of the ZnO nano-powders and thin films was investigated by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM), respectively. The photoluminescence spectra of the thermally treated powder and thin films present a maximum emission ultraviolet peak at 384 nm for the ZnO powder and at 379 nm for the thin films. The presence of the strong emission peak around 380 nm confirms a ZnO structure. The absence of emission in the 400-500nm wavelength range states for the low content in defects and vacancies.