Ferroelectric Driven Exciton and Trion Modulation in Monolayer Molybdenum and Tungsten Diselenides

In this work, we show how domain-engineered lithium niobate can be used to selectively dope monolayer molybdenum selenide (MoSe2) and tungsten selenide (WSe2) and demonstrate that these ferroelectric domains can significantly enhance or inhibit photoluminescence (PL), with the most dramatic modulation occurring at the heterojunction interface between two domains. A micro-PL and Raman system is used to obtain spatially resolved images of the differently doped transition metal dichalcogenides (TMDs). The domain-inverted lithium niobate causes changes in the TMDs due to electrostatic doping as a result of the remnant polarization from the substrate. Moreover, the differently doped TMDs (n-type MoSe2 and p-type WSe2) exhibit opposite PL modulation. Distinct oppositely charged domains were obtained with a 9-fold PL enhancement for the same single MoSe2 sheet when adhered to the positive (P+) and negative (P–) domains. This sharp PL modulation on the ferroelectric domain results from different free electron or ...