Quantifying the composition dependency of the ground-state structure, electronic property and phase-transition dynamics in ternary transition-metal-dichalcogenide monolayers

Abstract

Exploring ternary TMD (transition metal dichalcogenide) monolayers by alloying the typical binary TMDs is significant given their extremely wide applications due to their rich polymorphism and abundant electronic features. However, the fundamental properties of the large ternary TMD family including the structural/electronic diversities remain to be clarified. In the present work, by using comprehensive theoretical calculations, first, the critical concentration of the dopant that can trigger the ground-state structure change (GSC) of the TMD monolayers was identified and was found to be almost linearly linked to the concentration of the holes/electrons brought in by the dopant while being independent of the specific type of a dopant. Second, dopants that could induce the semiconductor–metal transitions (SMT) of the H phase of the group VIB TMDs were screened. Most importantly, the occurrence order of GSC and SMT was established with the increase in the doping concentration, which should be very informative for material designers desiring a specific “structure–property” relationship. The H–T′ phase transition barrier of group VIB TMDs could be significantly reduced by the small-sized dopant of group IVB, arising from the reduction of the electronic states at the Fermi level of the transition structure. Our findings deepen the understanding of ternary TMD monolayers and provide a valuable guideline for their wide applications.