Synthesis of pyrite thin films and transition metal doped pyrite thin films by aerosol-assisted chemical vapour deposition†‡
Diethyldithiocarbamato-metal complexes of the general formula [M(S2CN(Et)2)n] (M = Fe(III), Co(III), Ni(II), Cu(II), Zn(II) and n = 2, 3) have been synthesized and used as precursors for the deposition of iron pyrite (FeS2) and transition metal doped iron pyrite (MxFe1−xS2) thin films on glass and indium tin oxide (ITO) coated glass substrates by aerosol assisted chemical vapour deposition (AACVD). Thermogravimetric analysis (TGA) confirmed that all the five complexes decompose into their corresponding metal sulfides. The iron complex [Fe(S2CNEt2)3] (1) deposited pure cubic pyrite (FeS2) films with granular crystallites at 350 °C, whereas at 450 °C pyrite and marcasite were deposited. MxFe1−xS2 (where M = Co, Ni, Cu, or Zn) films were deposited by varying the relative concentration of complexes [Fe(S2CNEt2)3] (1) and [Co(S2CNEt2)3] (2), [Ni(S2CNEt2)2] (3), [Cu(S2CNEt2)2] (4) and [Zn(S2CNEt2)2] (5) at 350 °C. The formation of a solid solution was confirmed by powder X-ray diffraction (p-XRD). The surface morphology of the films was studied by scanning electron microscopy (SEM) whilst the height profiles of the films were revealed by atomic force microscopy (AFM). The elemental compositions of the films were confirmed by energy-dispersive X-ray (EDX) spectroscopy. To the best of our knowledge, these complexes are the first in their class to be used as single source precursors to deposit MxFe1−xS2 thin films.