THE GRADUATE SCHOOL OF NATURAL AND APPLIED SCIENCES OF MIDDLE EAST TECHNICAL UNIVERSITY
STRUCTURAL AND OPTOELECTRONIC PROPERTIES OF SOL-GEL DERIVED NICKEL OXIDE THIN FILMS
Nanocrystalline nickel (II) oxide (NiO) thin films were deposited on glass substrate by spin coating of sol-gel derived solutions. Thin film formation behavior and microstructural / physical properties of the films were investigated as a function of controllable processing parameters, such as thin film thickness and post deposition heat treatment (annealing temperature) in the range of 400 – 500 °C. Microstructural, morphological and optoelectronic properties of NiO films was examined by scanning electron microscopy, atomic force microscopy, X-ray diffraction, UV-Vis spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and temperature-dependent resistivity measurements. It was shown that microstructurally homogeneous and pristine film formation with controllable particle size of 10 – 30 nm can be achieved in a reproducible manner through the sol-gel processing route.
Sol-gel derived films of variable thickness in the range of 60 – 170 (± 5 nm), exhibited a transparency of 80 % to 65 % in the visible range, negligible changing with annealing temperature. This work presents a parametric optimization approach of solgel deposition of NiO thin films and their optoelectronic characteristics.
Keywords: P-type transparent oxide thin films; Nickel oxide; Sol-gel; Optoelectronic