Far-Reaching Remote Doping for Monolayer MoS₂ Using a Ferroelectric Substrate: Unveiling the Impact of h-BN Spacer Thickness

The damage-free doping of single-layer transition-metal dichalcogenides (TMDs) is crucial in the development of lateral two-dimensional (2D) electronics and optoelectronics. This can be achieved by remote carrier doping through an insulating barrier. This paper proposes a remote carrier density modulation method for TMDs using a ferroelectric substrate and thick hexagonal boron nitride (h-BN) spacer layers between 2 and 60 nm. Photoluminescence measurements of monolayer molybdenum disulfide on a periodically poled magnesium oxide-doped lithium niobate substrate showed that ferroelectric doping can be achieved even with h-BN spacer layers. Dissimilar to other remote doping, our research demonstrates a significant advance in remote doping capable of extending over 10 nm from the ferroelectric substrate. To explain our results, we employ three-dimensional Thomas–Fermi theory models, which suggest that the h-BN-thickness-dependent doping effect can be attributed to the dielectric screening property of h-BN. This enables the remoted doping to keep a flat interface of h-BN/TMDs, which could provide a promising route toward damage-free remote doping for TMDs, thereby enhancing the performance of nanoscale 2D TMD-based electronic and optoelectronic devices.