First Principles Study of Multiparticle Excitations in Monolayer MoTe₂

Monolayers of transition-metal dichalcogenides (TMDC), such as MoS₂, WSe₂, and MoTe₂, have opened the door to the theoretical and experimental studies of multiparticle excitations, such as trions and biexcitons, with relatively large binding energies. Upon carrier doping or strong optical pump fluence, these excitation complexes dominate the optical properties of these materials owing to the strong Coulomb interactions and reduced electronic screening in such systems. In this work, we perform first-principles calculations to study multiparticle excitations in monolayer MoTe₂. We employ interacting Green’s-function-based method, including the Bethe-Salpeter equation approach and beyond, to compute the interaction kernel for these multiparticle excitations, and utilize interpolation techniques to accurately resolve the spatially correlated features of such excitations. Our calculations allow us to resolve in fine detail the valley- and momentum-distribution of such multiparticle excitations for the lowest- and higher-energy trions, which differ significantly from simplified hydrogenic models. We also incorporate the dependence of the carrier doping in our calculations from first principles, and comment on the applicability of the traditional trion picture of one exciton plus an electron compared to the hybrid exciton plus Fermi-sea description to capture such excitations from first principles.