Determination of optical constants and band gap variation of Zn0.98-xCu0.02MgxO thin films

Cu doped ZnO (ZnCuO) is a very important candidate for electronic applications, since it has been shown that it possesses p–type conductivity. In order to broaden its applications, it is crucial to tune optical and electronic properties. In this study, by doping ZnCuO with magnesium, variation of refractive index, extinction coefficient, and band gap of thin films were investigated. Optical constants were evaluated using a transmittance model which is derived from Fresnel equations. Refractive indices of thin films were expressed as a dispersion relation in a polynomial form, while extinction coefficients were modelled as a convolution by Lorentzian curves. It was observed that magnesium doping decreased the refractive index and also caused a blue shift in absorption edge which is a clear indicator of band gap widening.

Keywords:

Doping, refractive index, sol-gel, thin films ZnO,

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