2023 COES Design and Research Conference

The Semiconductor-to-Metal Transition of W1-xTaxS2

Team Member: Elizabeth McDowell

Advisor: Dr. Pedro Derosa

Transition metal dichalcogenides (TMDs) are a type of two-dimensional materials notable for their widely tunable electronic properties, making them valuable components for transistors, solar cells, sensors, and other important applications. While TMDs are widely studied as semiconductors, some TMDs, like TaS₂, have metallic properties. Heterogeneous monolayers with two or more transition metals have been studied; however, the effect of combining transition metals of different periodic groups has not been fully explored. This study examines the effect of doping WS₂ with a transition metal adjacent to tungsten, namely tantalum, as a function of the concentration and the relative position of the doping atoms. To obtain this data, density functional theory calculations were performed using the software, QuantumATK. Band structure and density of states were used to understand the electronic properties of the monolayers. The data showed that doping WS₂ with tantalum resulted in band structures consistent with p-type doping with concentration-dependent electronic properties. In addition, we observed that the band gap depends on the relative position of the dopants. The semiconductor-to-metal transition of W₁-xTaxS₂ occurred between x = 0.04 and 0.10, depending on the locations of the Ta atoms. The effect of the relative position of doped atoms has not been discussed in the literature, so these findings will improve the understanding of heterogeneous monolayer TMDs and potentially impact the design of heterostructures with uniquely tailored properties.

Program Awards Ceremony