Structural, morphological, optical and third order nonlinear optical response of spin-coated NiO thin films: An effect of N doping.

Abstract The present work deals with the deposition of NiO and Nitrogen (N)-doped NiO thin films by sol-gel spin coating technique. Structural, morphological, linear and non-linear optical characteristics of undoped and N-doped (1–15 wt%) NiO films were studied. From XRD measurements, it is evident that single phase nano crystalline NiO is formed for all doping concentrations. Surface morphology study shows that higher concentration of N doped NiO thin films were of high quality and EDX mapping confirmed the doping of Nitrogen in films. The Raman spectra of the studied films were analyzed over the range of 1400-200 cm−1. The optical studies confirm that as doping increases, transparency of the film decreases (except at 10% N doping) and the band gap narrows. Nonlinear parameters such as refractive index and susceptibilities also depend on N dopant concentration. Z-scan studies viz., absorption index, nonlinear refractive index were carried out on undoped and N doped NiO samples and the results were matched with theoretical calculated values. Graphical abstract Image 1 Highlights • N doped NiO films were deposited by spin coating technique. • UV-Vis-NIR study confirms high optical transparency of deposited films. • Direct energy gap was reduced from 4 eV to 3.8 eV due to n doping. • Third order nonlinear properties are enhanced due to N doping. • Values of n 2 and β are found to be of order of 10−7 and 10−2 esu, respectively. [ABSTRACT FROM AUTHOR]