Growth and Surface Characterization of a Type-II ZnO/ZnS Heterostructure
P. E. S. de Oliveira, Ivan Evangelista do Vale Coelho, Guilherme Félix, Pedro Venezuela, Fernando Stavale
Abstract
High Resolution Image Download MS PowerPoint Slide We report the in situ formation of a type-II ZnO/ZnS heterostructure via the thermal oxidation of a ZnS(001) single crystal under a clean controlled oxygen atmosphere. By combining X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), we investigated the chemical composition, electronic structure, and surface morphology of the resulting interface. Core-level shifts observed in our XPS measurements suggest an upward band-bending due to the formation of a hybrid interface. AFM measurements show that ZnO grows through a layer-plus-island mode, forming distorted hexagonal nanoislands. Our band alignment analysis confirms the type-II heterostructure arrangement with suitable electronic band-edge positions for efficient charge separation, highlighting its potential as a platform for photocatalytic applications, such as hydrogen and oxygen evolution reactions (HER and OER).