Synthesis and structure of nickel doped tin oxides based films

Structural investigations of nickel-doped tin oxide films has been carried out using X-ray diffraction and Raman spectroscopy. The films were synthesized by magnetron sputtering of a tin target with nickel inserts (1-2 strips with width of 2 mm) in argon-oxygen plasma (with oxygen content in range of 0-6 vol. %), followed by 2-stage annealing in air (at the temperature of about 200℃ during 2 hours at the first stage followed by heating and isothermal annealing during 1 hour and at the temperature of 375℃). It was found that films obtained in argon plasma (without oxygen) have a polycrystalline structure, which includes SnO and SnO₂ phases, as well as nonstoichiometric phases Sn₂O₃, Sn₃O₄. Using of 2 nickel inserts in a tin target during magnetron sputtering induces the formation of a more disordered structure of tin oxide films. Using of reactive magnetron sputtering of a tin target with 2 nickel strips (with an oxygen content of 2 vol. %) leads to further smearing of tin oxides characteristic lines in X-ray diffraction patterns and Raman spectra of nickel doped tin oxide films. Films synthesized by magnetron sputtering in argon-oxygen plasma with an oxygen content of 4-6 vol. % with the following annealing in air have an amorphous structure. (authors)