The energy band alignment at the interface between mechanically exfoliated few-layer NiPS3 nanosheets and ZnO

• We fabricated few-layer NiPS3 nanosheets on ZnO/Nb:SrTiO3 by mechanical exfoliation method.
• Insertion of ZnO layer enhances visibility of few-layer NiPS3 and prevents charging effects for photoemission studies.
• The band offset of NiPS3/ZnO is determined using micro-beam XPS measurements.
• Type-II band alignment is observed at the interface of NiPS3 and ZnO.
• The values of valence band offset increase as NiPS3 layer number decreases.

We have studied the electronic structure and interfacial properties of mechanically exfoliated few-layer NiPS3 van der Waals crystals on ZnO/Nb:SrTiO3 substrates using scanning photoelectron microscopy and spectroscopy. The conducting ZnO layer enhances the visibility of few-layer NiPS3 on Nb:SrTiO3 and prevents charging effects in photoemission. We experimentally determined a type-II band alignment at the NiPS3/ZnO interface. The valence band offset (VBO) of few-layer NiPS3/ZnO is 2.8 ± 0.09 eV, and the conduction band offset is 1.0 ± 0.09 eV. Moreover, we found an increase of ∼0.3 eV in VBO as decreasing NiPS3 thickness, suggesting electronic coupling or charge transfer at the NiPS3/ZnO interface.

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