Single source heterobimetallic precursors for the deposition of Cu–Ti mixed metal oxide thin films

Abstract

Heterobimetallic molecular precursors [Ti₄(dmae)₆(µ-OH)(µ-O)₆Cu₆(benzoate)₉] (1) and [Ti₄(dmae)₆(µ-OH)(µ-O)₆Cu₆(2-methylbenzoate)₉] (2) were prepared by the interaction of Ti(dmae)₄ [dmae = N,N-dimethylaminoethanolate] with Cu(benzoate)₂·2H₂O for (1) and Cu(2-methylbenzoate)₂·2H₂O for (2), respectively, in dry toluene, for selective deposition of Cu/Ti oxide thin films for possible technological applications. Both the complexes were characterized by melting point, elemental analysis, FT-IR, thermal analysis and single crystal X-ray analysis. Complex (1) crystallizes in the triclinic space group P-1 and complex (2) in the rhombohedral space group R-3. The TGA analysis proves that complexes (1) and (2) undergo facile thermal decomposition at 550 °C to form copper titanium mixed metal oxides. The SEM/EDX and XRD analyses suggest the formation of carbonaceous impurity free good quality thin films of crystalline mixtures of β-Cu₃TiO₄ and TiO₂ for both (1) and (2), with average grain sizes of 0.29 and 0.74 µm, respectively. Formation of two different homogenously dispersed oxide phases is also supported by electrical impedance measurements.