Synthesis, structural and electrical characterizations of thermally evaporated Cu2SnS3 thin films
Ternary compound of Cu2SnS3 thin films were grown on microscopic glass substrates. The bi-layer of metallic Cu-Sn precursors were first deposited sequentially on microscopic glass substrates at the controlled thickness of 100nm, 500nm and 1000nm and at different substrate temperatures of 270C, 1000C and 2000C using Thermal Evaporation technique. The depositions were uniformly spread on the glass substrates. The films were subsequently sulphurized in a custom-built reactor for 60 minutes at 4000C. The micrographs from Scanning Electron Microscope show that the grain size increases to about 2μm with increasing substrate temperature from 270C to 2000C. Energy Dispersive X-Ray System (EDS) identified Cu, Sn, S and glass substrate constituents such as Na, Si, Mg and O with their percentage composition in the deposited ternary film. The surface profilometer shows that the deposited films are rough. The XRD spectra identified the crystal structure, phases and lattices as Cubic Cu2SnS3 [1 1 1], Anorthic Cu2SnS3 [-2 0 0 ] and Monoclinic Cu2SnS3 [-1 3 1]. The electrical characteristics of the deposited Cu2SnS3 films were determined by Semiconductor Characterization System and Four Point probe. The cross-planar i-v characteristics curves of Cu2SnS3 films were non-Ohmic while in-planar i-v characteristic curves were Ohmic. The electrical resistivity of the deposited Cu2SnS3 film is 2.55 x 10-3 Ωcm. The conductivity is in the order of 103 Ω-1cm-1.
Key words: Ternary compound, microscopic glass substrate, Thermal Evaporation, Sulphurization, Micrographs and Electrical Resistivity.