Bi-MoSe₂ Contacts in the Ultraclean Limit: Closing the Theory-Experiment Loop

Achieving robust electrical contacts is crucial for realizing the promise of monolayer 2D semiconductors such as semiconducting transition metal dichalcogenides (s-TMDs) in electronics. Despite recent breakthroughs, a gap remains between the experimental and theoretical understanding of metal-s-TMDs contacts. This study explores bismuth semimetal contacts to monolayer MoSe₂, using a platform that minimizes experimental sources of uncertainty; we combine contact-front and contact-end measurements to measure key parameters like specific resistivity (ρ_c) and transfer length (L_t). We find that the resistivity of MoSe₂ under the contacts is enhanced due to charge transfer that can be modeled using a self-consistent approach. In contrast, ab initio calculations of the interlayer charge transfer rate are inconsistent with the measured value of ρ_c, highlighting the need for new theoretical approaches.