Analysis of the heterojunction band offset of h-BN/TMDCs

In order to analyze the effect of the chalcogen on the band alignment of the Transition metal dichalcogenides (TMDCs) and hexagonal Boron Nitride (h-BN) heterojunction, we fabricated the h-BN/TMDCs heterojunction by vertically stacking mono-layer h-BN and multi-layer TMDCs by the wet transfer method. The four heterojunctions are h-BN/WS2, h-BN/WSe2, h-BN/MoS2 and h-BN/MoSe2. X-ray photoelectron spectroscopy (XPS) has been employed to ascertain the Valence Band Offset (VBO) at the junctions created among these heterojunctions. All heterojunction band alignment styles are type-I. When the chalcogen changes from S to Se, the heterojunction VBO values increase. Specifically, in case of h-BN/WS2 and h-BN/WSe2 the VBO is 2.42 eV and 2.81 eV, respectively, and the magnitude of the difference is 0.39 eV. In the same case for h-BN/MoS2 and h-BN/MoSe2 the VBO is 2.52 eV and 2.55 eV, respectively, and the magnitude of the difference is 0.03 eV. The aforementioned research has obtained the band alignment for four heterojunctions, which provides a valuable reference for the design and analysis of the correlation devices in the future.