Competing sublattice short-range orders and gap state engineering in multicomponent transition-metal dichalcogenide

Discovering new materials with desirable band gap and gap state is a central task in the semiconductor community, primarily relying on composition modulation. In this work, by employing atomic simulations, using transition-metal dichalcogenide Re_0.5Nb_0.5(S_0.5X_0.5)₂ (X=Se, Te) monolayer as an example, we present an alternative avenue for gap state engineering via leveraging diverse chemical short-range orders (SROs). It is found the electronic state contributed by the SRO motif tends to be occupied and may merge with the valence band, yielding a clean band gap in these multicomponent systems. On the contrary, the energy unfavorable local configurations, can produce localized states. The chemical environment in the chalcogen sublattice which has negligible influence on the band gap size can further fine-tune the gap states. The strong coupling of multiple short-range orders and gap states revealed in our work unlock the potential application of a vast family of multicomponent semiconductors.