^aCenter of Nanotechnology, King Abdulaziz University, Jeddah 21589,

Saudi Arabia

^bMaterials Science and Nanotechnology Department, Faculty of Postgraduate

Studies for Advanced Sciences, Beni–Suef University, Beni–Suef 62511, Egypt

^cElectron Microscope and Thin Films Department, Physics Research Division,

National Research Centre, Dokki, Giza 12622, Egypt

The effect of annealing the substrate on the structural and optical properties of the nickel oxide thin films containing a fixed ratio of molybdenum was investigated. Energy- dispersive X-ray spectroscopy (EDX) revealed that the Mo ratio is 4.41 wt%. X-ray diffraction (XRD) revealed that the formed films comprise a phase of NiO0.96. The average crystallite size, dislocation density, and strain function were calculated. Atomic force microscopy (AFM) was employed to investigate the morphology and surface roughness.

With the increase in the substrate temperature from 298 K to 673 K, the optical band gap values varied from 3.72 eV to 3.58 eV.