Giant Trion Modulation in Scalable Monolayer MoS₂ via Plasmonic HfN Gates
Summary of Achievement
A research team led by RCAS researcher Prof. Yu-Jung Lu recently published their findings in Nature Photonics. Working in collaboration with Prof. Vincent Tung from the University of Tokyo, Prof. Lu and her collaborators demonstrated efficient trion modulation in MoS₂ enabled by plasmonic HfN gates. PL modulation depth of ~24% was achieved over large area tunable regions. Monolayer two-dimensional (2D) transition metal dichalcogenides offer strong excitonic responses and gate-tunable optical properties, making them attractive for next-generation photonic and optoelectronic devices. However, achieving wafer-scale, room-temperature operation with a high photoluminescence (PL) modulation depth remains a key challenge owing to the limited electrostatic control and inefficient light–matter coupling. Here, we overcome this challenge with a scalable, electrically tunable light-emitting platform that integrates monolayer MoS₂ with a work-function-controllable hafnium nitride (HfN) gate electrode. The favorable band alignment enables efficient charge accumulation and giant trion modulation, yielding a PL modulation depth of ~ 24%, five times stronger than that of p⁺-Si gates, across tunable regions exceeding 5,000 μm². To further amplify the emission, we introduce resonant nanoparticle-on-mirror (NPoM) plasmonic cavities, achieving a 46-fold emission enhancement due to the Purcell effect while preserving the gate-tunable trion control. Finite-difference time-domain (FDTD) simulations reveal strong optical field confinement in the NPoM cavity, which facilitates efficient plasmon–trion coupling. The results demonstrate a room-temperature, CMOS-compatible approach for realizing actively reconfigurable 2D light sources, paving the way for on-chip integrated photonics, visible light communication, tunable emission platforms, and advanced active control of light–matter interactions in two-dimensional systems. The research was published in Nature Photonics on May 25, 2026. The first author is Tzu-Yu Peng, a Ph.D. student at the Graduate Institute of Applied Physics, National Taiwan University. Cheng-Han Lin is listed as a co-first author and is currently affiliated with Micron Technology. The co-authors include Dr. Min-Hsiung Shih's team at RCAS, who assisted with optoelectronic characterization; Dr. Hung Wei Shiu at NSRRC, who conducted the UPS measurements; and Dr. Liang-Yan Hsu's team at IAMS, who contributed to the theoretical many-body calculations. The research was supported by the Academia Sinica, the National Science and Technology Council, and the Japan Science and Technology Agency (ASPIRE).
Giant Trion Modulation in Scalable Monolayer MoS₂ via Plasmonic HfN Gates
The research team led by Associate Research Fellow Yu-Jung Lu at the Research Center for Applied Sciences, Academia Sinica, has long been dedicated to developing transition-metal nitride thin-film materials with plasmonic properties and further integrating them into quantum optoelectronic devices. Their work spans device design, fabrication, and optoelectronic characterization.
The research team led by Professor Vincent Tung in the Department of Chemical Engineering at the University of Tokyo, Japan, has long been engaged in developing wafer-scale growth technologies for single-crystalline monolayer two-dimensional materials, providing a critical materials foundation for large-area two-dimensional semiconductor devices.
