Asymmetric gate modulation induced by device geometry in dual-gated WSe2 and WS2 transistors

Two-dimensional (2D) transition metal dichalcogenides have enabled new opportunities for exploring electrostatic control and contact engineering in atomically thin semiconductors. Here, we study dual-gated WSe2 and WS2 field-effect transistors with a fully top-gated geometry, where the WSe2 and WS2 films continuously cover bottom metal contacts. The devices exhibit markedly different transport characteristics under top- and bottom-gate modulation, revealing the impact of electrostatic screening by metal electrodes. Our results demonstrate how device geometry and gate configuration govern the spatial extent of field-effect control and carrier injection, offering insights into contact-gate coupling in 2D semiconductor systems.