A comparative analysis for effects of solvents on optical properties of Mg doped ZnO thin films for optoelectronic applications

Nanocrystalline Magnesium doped ZnO thin films (MgZnO) were synthesized on glass substrate using five different solvents i.e. 1-Propanol (1Pd), 2-Propanol (2Pd), Ethanol (Ed), Methanol (Md) and 2-Methoxyethanol (MEd) by sol-gel spin coating method. This study targeted the best solvent with MgZnO film for optoelectronic applications. The magnesium doping percentage was fixed at 5% for all samples to discover comparatively better doped results among different solvents. All the films synthesized by different solvents exhibited polycrystalline structure, particularly films with 1-Propanol and 2-Methoxyethanol showed preferred c-axis orientation at 180 degrees C pre-heating condition revealed by XRD pattern. Highest average crystallite size calculated by XRD study was for 2-Methoxyethanol solvent which possessed good crystalline quality. Crystalline quality was also confirmed by Raman analysis. FESEM images elucidated that all the films were crack free, had uniformly smooth grains and highest grain size for 2-Methoxyethanol solvent. EDS and FTIR spectra confirmed the magnesium presence in ZnO thin films for all solvents. The optical absorbance, transmittance and reflectance spectrum were analyzed by UV-vis spectroscopy. The highest transmittance (94 %), band gap value (3.36 eV) and better quality by PL analysis in comparison were found for 2-Methoxyethanol solvent. The data for optical constants were measured by spectroscopic ellipsometry. Furthermore real and imaginary parts of complex dielectric constant and energy loss functions were examined.