Investigating synthesis of Cu2ZnSn(Se1-x,Sx)4 for values of 0≤x≤1 by S for Se substitution and direct sulphidisation of metallic precursors

Thin layers of Cu2ZnSn(Se1-x,Sx)4 were produced by selenisation and subsequent sulphur substitution of DC sputter-deposited metallic CZT precursors on soda-lime glass. Values of x=(0, 0.07, 0.12, 0.17, 0.28, 1) were measured by EDS. Samples were characterised optically and analysed using the Kubelka-Munk function, and found to have 0.96eV ≤Eg≤ 1.47eV, varying approximately linearly with x. Samples underwent X-ray diffraction characterisation and substituted samples were found to comprise of multiple phase kesterite material with different levels of S substitution, averaging to the values obtained by EDS. The spectra were found to conform to Vegard's law, as peak location shifted linearly between x=0 and x=1. Binary phases are suspected to exist, because of some unusual behaviour at the location of the (200) peak. Lattice parameters for all phases were calculated and found to vary linearly between (a=b=5.692, c=11.338) for x=0 and (a=b= 5.393, c= 10.863) for x=1, which are in excellent agreement with previously published figures.