In situ growth of a type-II ZnO/ZnS heterostructure:From stability to band-offset

TL;DR

This study demonstrates the in situ growth of a stable type-II ZnO/ZnS heterostructure with potential catalytic applications, characterized by band-bending and island formation through controlled oxidation.

Contribution

It introduces a novel method for synthesizing a stable ZnO/ZnS heterostructure via controlled oxidation, with detailed analysis of its electronic and morphological properties.

Findings

Formation of a hybrid ZnO/ZnS interface with band-bending effects.

Observation of ZnO/ZnS-like islands on the surface.

Type-II band alignment suitable for catalytic applications.

Abstract

We have successfully obtained a ZnO/ZnS heterostructure by heating a ZnS(001) single crystal in a controlled impurities-free oxygen atmosphere. Combining X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM), we explore the stability, electronic structure, and morphology of that interface. Our XPS measurements reveal a binding energy shift of the core-level peaks, indicating a band-bending effect due to the formation of a hybrid ZnO/ZnS interface. In addition, AFM measurements show that exposure of ZnS single-crystal to an oxygen atmosphere leads to the formation of ZnO/ZnS-like islands. Interestingly, our band-offset estimation suggest a type-II heterostructure arrangement with suitable electronic edges positions that turn ZnO/ZnS heterostructure a promising platform for catalytic applications, particularly hydrogen and oxygen evolution reactions.