Band gap widening of nanocrystalline nickel oxide thin films via phosphorus doping

Phosphorus doped nanocrystalline NiO thin films were synthesized using radio frequency magnetron sputtering of a prefabricated target on glass and silicon substrates in argon atmosphere. X-ray diffraction studies confirmed the good crystallinity and proper phase formation. Phosphorus doping in NiO films was confirmed from the binding energy determination by X-ray photoelectron spectroscopic studies. Morphological information was obtained from the atomic force microscopic measurement. Determination of band gaps from the UV–vis–NIR spectrophotometric measurement showed that it increased from 3.66 to 3.81 eV corresponding to undoped and 10% P doped NiO thin films.