Structural phase transitions in a MoWSe2 monolayer: Molecular dynamics simulations and variational autoencoder analysis

Abstract

Electrical and optoelectronic properties of two-dimensional (2D) transition metal dichalcogenides (TMDCs) can be tuned by exploiting their structural phase transitions. Here semiconducting (2H) to metallic (1T) phase transition is investigated in a strained ${\mathrm{MoWSe}}_{2}$ monolayer using molecular dynamics (MD) simulations. Novel intermediate structures called $\ensuremath{\alpha}$ and $\ensuremath{\beta}$ are found between the 2H and 1T phases. These intermediate structures are similar to those observed in a 2D $\mathrm{Mo}{\mathrm{S}}_{2}$ by scanning transmission electron microscopy. A deep generative model, namely the variational autoencoder (VAE) trained by MD data, is used to generate novel heterostructures with $\ensuremath{\alpha}$ and $\ensuremath{\beta}$ interfaces. Quantum simulations based on density functional theory show that these heterostructures are stable and suitable for novel nanoelectronics applications.