Preparation and Characterization of Cu-doped ZnO Sol-gel Derived Optical Thin films

In this work, we report the preparation of Cu-doped ZnO thin films by sol-gel method based on zinc acetate dihydrate (CH3COO)(2)Zn center dot 2H(2)O, Copper acetate dihydrate Cu-3(CH3COO)(2)center dot H2O) and diethanolamine (HN(CH2OH)(2), DEA). The precursor solution was prepared at various Cu composition ranging from 2-20 wt%. All films were spin-coated on borosilicate substrates for several coating repetition followed by annealing process at 550 degrees C for 4 h in an ambient air. The structural properties of the films were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD results indicate the domination of hexagonal wurtzite structure of ZnO with noticeable alternation in the XRD peak intensity upon Cu doping content. SEM results revealed the grain size shape and surface morphologies of as-prepared samples. Crucial optical properties of as-prepared films were scrutinized from their UV-Vis transmission spectra. The films are highly transparent in the visible region with more than 90 % transparency within 380 nm to 800 nm. Their corresponding band gaps indicate significant red shift with increasing Cu doping content. Overall results suggest that Cu additive play a vital role on relevant optical properties of ZnO that can be adjusted to meet the requirement for practical optoelectronics applications.