Drop-Dry Deposition of Ni(OH) Precursors for Fabrication of NiO Thin Films.

Drop-dry deposition (DDD) is a method of depositing thin films by heating and drying the deposition solution dropped on a substrate. We prepared Ni(OH) precursor thin films by DDD and annealed them in air to prepare NiO thin films. The appropriate deposition conditions were found by changing the number of drop-dry cycles and the concentrations of chemicals in the solution, and the Ni(OH) precursor film with a thickness of 0.3 μm and optical transmittance of more than 95% was successfully deposited. Raman and X-ray diffraction measurements were performed, and it was found that the NiO film was successfully fabricated after annealing at 400 °C. The p-type conductivity of the annealed film was confirmed by photoelectrochemical measurements. In addition, we prepared n-type ZnO by electrochemical deposition on NiO thin films. The current-voltage measurement results show that the ZnO/NiO heterojunction had rectification properties.