Galvanostatically-electrodeposited Cu-Zn-Sn multilayers as precursors for crystallising kesterite Cu2ZnSnS4 thin films

Metallic stacked layers containing Cu, Zn and Sn on Mo-coated glass substrates were prepared by galvanostatic electrodeposition as precursors for crystallising kesterite Cu2ZnSnS4 films. Due to the nature of the MoOx passivating layer on the Mo surface, initial trials were particularly addressed to deposit strong adhesive precursors by firstly depositing Cu layers on Mo-coated substrates from acidic as well as alkaline solutions. It was found that the acidic Cu solutions were not appropriate for the Cu deposition on Mo-coated glass substrates, since they led to an inhomogeneous coverage of the Cu deposits in addition to extremely poor adhesion. In contrast, utilising an alkaline Cu solution yielded a homogeneous coverage of the Cu deposits, having strong adhesion to the Mo-coated glass substrates, which was essential for the subsequent acidic Zn or Sn galvanostatic electrodepositions. The crystallisation of kesterite Cu2ZnSnS4 from metallic stacked Cu/Sn/Zn precursors was investigated as well. The sulfurisation process crystallises the Cu-Zn-Sn precursor films into films exhibiting predominant kesterite phase. This result demonstrates that the established galvanostatic electrodeposition technique for metals has a technological potential for preparing kesterite precursors.