2025/04/29 by Lauren Hoang, Robert K. A. Bennett, Hoang, Lauren +17 · 1 citation
Materials Science · Physics and Astronomy · #2D Materials and Applications #Graphene research and applications #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.2504.21102
Tungsten diselenide (WSe2) is a promising p-type semiconductor limited by high contact resistance (R_\textrmC) and the lack of a reliable doping strategy. Here, we demonstrate that exposing WSe2 to chloroform provides simple and stable p-type doping. In monolayer WSe2 transistors with Pd contacts, chloroform increases the maximum hole current by over 100× (>200 μA/μm), reduces R_\textrmC to ~2.5 kΩ⋅μm, and retains an on/off ratio of 1010 at room temperature. These improvements persist for over 8 months, survive annealing above 150 °C, and remain effective down to 10 K, enabling a cryogenic R_\textrmC of ~1 kΩ⋅μm. Density functional theory indicates that chloroform strongly physisorbs to WSe2, inducing hole doping with minimal impact on the electronic states between the valence band and conduction band edges. Auger electron spectroscopy and atomic force microscopy reveal that chloroform intercalates at the WSe2 interface with the gate oxide, contributing to doping stability and mitigating interfacial dielectric disorder. This robust, scalable approach enables high-yield WSe2 transistors with good p-type performance.