ZnS, CdS and Zn x Cd 1-x S Thin Films from Zn(II) and Cd(II) Complexes of 1, 1, 5, 5- Tetramethyl -2-4-dithiobiuret As Single Molecular Precursors Karthik Ramasamy , Mohammad A.Malik, Paul O’Brien * and James Raftery School of Chemistry, Materials Science Centre, The University of Manchester, Manchester, M13 9PL, UK ABSTRACT Synthesis of zinc and cadmium complexes of 1, 1, 5, 5-tetramethyl-2-4-dithiobiuret (M{N(SCNMe 2 ) 2 } 2 ) (M = Zn, Cd) is described together with X-ray single crystal of cadmium complex. These complexes have been used as a single molecular precursor for the deposition of ZnS, CdS and Zn x Cd 1-x S thin films by aerosol assisted chemical vapour deposition (AACVD) method. Adherent specular films of ZnS and CdS were obtained in the temperature range 300 - 500 °C. Hexagonal Zn x Cd 1-x S films were obtained at 400 °C by varying the precursor concentration. XRD of ZnS films showed cubic to hexagonal phase conversion above 350 °C. SEM showed that the morphology of the films varied depending on the deposition temperature. Films were also characterized by atomic force microscopy (AFM). To the best of our knowledge these complexes are the first in its class to be used as a single molecular precursor to deposit ZnS, CdS, and Zn x Cd 1-x S thin films. INTRODUCTION ZnS and CdS thin films have been used for a wide variety of technological applications including solid state cell windows, electro- optic modulators, sensors, electroluminescent and photo luminescent devices and anti reflection coatings [1-4]. In particular such systems have been widely employed in display technology as host lattices for doped phosphor materials, whose emission wavelength can be tailored as a function of dopant metal [2, 5-7]. The size and electronic structure of the cations are so similar; those materials readily form a continuous series of solid solutions [8]. Thus this is a system in which systematic variation of photoelectronic properties is possible simply by adjusting the composition of the solid solution. In the wurtzite structure ZnS and CdS have unit cell volume in the ratio Zn 2+ / Cd 2+ ≈ 0.77 [9]. Because of such qualitative similarities these materials have been widely employed as good candidate for the fabrication of p-n junction without lattice mismatch in devices based on quaternary materials such as CuIn x Ga 1-x Se 2 [10] or CuIn(S x Se 1-x ) 2 [11]. Thin films of Zn x Cd 1-x S [12,] are known to have properties in between those of ZnS and CdS. Because of the addition of ZnS, the Zn x Cd 1-x S band structure has a larger energy gap than CdS. This makes it much more attractive for the fabrication of window material in hetero junction photovoltaic solar cell [13]. Several techniques have been used to grow these materials including sputtering [14], pulsed laser ablation [15], spray pyrolysis [16], chemical bath deposition [17], electrostatic assisted aerosol jet deposition [18], sol-gel [19], Ion- beam deposition [20] and MOCVD [21]. Accordingly various single source precursors have been investigated such as dialkyl dithiocarbamates [22] and alkyl xanthates [21]. Herein, we report Zn and Cd complexes of 1,1,5,5 – tetramethyl -2- 4- dithiobiuret {M(SCNMe 2 ) 2 } 2 ]{M = Zn, Cd} as a single molecular precursor for deposition of ZnS, CdS and Zn x Cd 1-x S thin films by AACVD. Mater. Res. Soc. Symp. Proc. Vol. 1145 © 2009 Materials Research Society 1145-MM04-40