Nanostructured nickel oxide thin films were prepared by the pulsed laser ablation
technique. The effects of annealing on the structural, morphological, electrical and optical
properties are discussed. Phase imaging was used to examine the surface contaminants,
adhesion and hardness and height imaging to evaluate the height profile of the films.
Morphological investigations using atomic force microscopy and scanning electron
microscopy indicate a strong influence of the annealing process on the surface
roughness and particle size. A self-assembly of nanocrystals agglomerating together
to form an island-like structure is observed in films annealed at 773 K. X-ray
diffraction and x-ray photoelectron spectroscopy investigations indicate the presence of
Ni2O3
in the as-deposited films. A transformation to cubic NiO with growth along (111) and (200)
planes with increase of annealing temperature is also observed.
Postdeposition annealing of thin nickel films synthesized using R.F. magnetron sputtering technique is carried in this study. The XRD analysis indicates that annealing of the nickel films leads to the formation of nickel oxide with a preferential growth along (200) plane. The oxidation mechanism is observed with a phase transformation and results in polycrystalline NiO films. The surface morphology of the thin films was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) as a function of annealing temperature. The studies indicate the formation of well-defined grain boundaries due to agglomeration of nanocrystallites. The films annealed in the range 573–773 K are found to be porous. The optical transmission spectra of the films annealed at 773 K exhibit interference effects for photon energies below the fundamental absorption edge. The optical studies indicate the existence of direct interband transition across a bandgap of 3.7 eV in confirmation with earlier band structure calculations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.