Intermediate State between MoSe2 and Janus MoSeS during Atomic Substitution Process

Janus transition metal dichalcogenides (TMDCs), with dissimilar chalcogen atoms on each side of TMDCs, have garnered considerable research attention because of the out-of-plane intrinsic polarization in monolayer TMDCs. Although a plasma process has been proposed for synthesizing Janus TMDCs based on the atomic substitution of surface atoms at room temperature, the formation dynamics and intermediate electronic states have not been completely examined. In this study, we investigated the intermediate state between MoSe2 and Janus MoSeS during plasma processing. Atomic composition analysis and atomic scale structural observations revealed the intermediate partially substituted Janus (PSJ) structure. Combined with theoretical calculations, we successfully clarified the characteristic Raman modes in the intermediate PSJ structure. The PL exhibited discontinuous transitions that could not be explained by the theoretical calculations. These findings will contribute toward understanding the formation process and electronic-state modulation of Janus TMDCs.

Automated summary

This study investigates the intermediate state and characteristic Raman modes of Janus MoSeS during plasma processing. The intermediate partially substituted Janus (PSJ) structure is revealed through atomic composition analysis and atomic scale structural observations. The discontinuous transitions in the photoluminescence spectrum cannot be explained by theoretical calculations. These findings contribute to the understanding of the formation process and electronic-state modulation of Janus TMDCs.