Electrodeposition of polyphasic films of zinc oxi sulfide from DMSO onto n-InP(100) and n-InP(111) single crystals in the presence of zinc salt, thiourea, and dissolved molecular oxygen

In the present work, we studied the electrodeposition of zinc oxide sulfide films onto monocrystalline n-InP((111) over bar) and (100) substrates starting from the combined reduction of thiourea, as a sulfide ion source, and molecular oxygen in the presence of zinc ions using DMSO as the solvent. The possible reactions involved in the formation of the films were studied through cyclic voltammetry. Independent of electrodeposition potential or the crystalline plane employed, a peculiar honeycomb bee morphology was observed by SEM in the deposits. The films formed on both crystalline planes showed a variable composition that can be adjusted by changing the electrodeposition potential. The crystalline characterization of the films was studied through RHEED. In agreement with the atomic ratio obtained by EDS, the patterns obtained showed that the as-grown deposits are basically formed by ZnO, ZnO2, and ZnS. The polyphasic film composition can be represented by [(ZnO)(a)(ZnO2)(b)(ZnS)(c)], and a general formation reaction for this class of mixtures is proposed. The analysis of their optical properties for the polyphasic films formed onto FTO electrode gave a band gap of 3.46 eV, meaning that the films can be considered as a good alternative to a layer window in solar cells.