Influence of Ge content on Cu2Zn(SnGe)Se4 physical properties deposited by sequential thermal evaporation technique

In this research, we report the synthesis of Cu2Zn(SnGe)Se4 compound by sequential thermal evaporation technique as well as the influence of the germanium content on the electrical, optical, structural, morphological and chemical properties of this material. The order of the metallic stacks deposited on the coated molybdenum glass substrates was Cu/Sn/Cu/Zn/Ge. In order to obtain the Cu/(Zn+Sn) and Zn/Sn compositional ratios close to those considered as optimum, the thicknesses of Cu (3 nm)/Sn(248 nm)/Cu(105 nm)/Zn (174 nm) were kept constant and only the thickness of the Ge layer was varied between 10 nm and 50 nm. Subsequently, these stacks were heat treated in a selenium atmosphere to achieve crystallization of the compound. The incorporation of small amounts of germanium shows a growth in the grain size and a more compact surface morphology without modifying the optical properties.