Synthesis and characterization of high entropy stabilized (BaxSrxMnxfexNix) Zn1-5xO thin films obtained by spray pyrolysis

Abstract

In recent years, the concept of high‐entropy alloys and oxides, has led to an increased impact on research communities due to their unique structural characteristics and correlated possibilities for tailoring of functional properties. Configurational disorder in a lattice structure can be compositionally engineered by modifying a single sublattice with many distinct cations. These types of metallic alloys and ceramic compound’s novel structures are known as high entropy stabilized structures. Based on this concept, we explored this study to focus the stabilization of ZnO wurtzite single phase structure though high level multielement (Ba, Sr, Mn, Fe and Ni) doping with the assistance of entropic contribution. For this purpose thin films of pure ZnO and doped (BaxSrxMnxFexNix) Zn1-5xO (where x=0.01, 0.02 and 0.03) were deposited through low cost spray pyrolysis technique. Important spray pyrolysis parameters were maintained as substrate temperature: 200°C, precursor solution concentration: 0.12M, solution flow rate: 0.5 ml/minute and spray outlet to substrate distance: 30cm. The fabricated undoped and doped films were entitled as ZO, 5DZO (x=0.01), 10DZO (x=0.02) and 15DZO (x=0.03). To characterize the structural, morphological, optical and electrical properties of as-deposited films, X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Visible spectroscopy, FTIR spectroscopy, I-V measurements and impedance analysis were conducted. The detailed structural characterization showed the entropic contribution in single phase stabilization of highly doped 15DZO. XRD result and Reitveld refinement confirmed successful doping of five elements in ZnO with slight lattice parameters change. Well distributed homogeneous fine particles surface morphology was observed after doping in SEM characterization. Very good optical properties (i.e. transmittance about 98%, energy band gap increment from 3.37 eV to 3.8 eV and optical conductivity enhancement) were found in doped films that deserves high application potentials as TCOs and LED. Electrical conductivity, capacitance and other properties were also changed in doped films with promising outcomes.