Gate-Tunable Emission in Scalable Monolayer MoS₂ Integrated with Nitride-Based Plasmonic Heterostructures

Mechanically exfoliated monolayer molybdenum disulfide (MoS₂) exhibits outstanding optoelectronic properties, making it highly desirable for photonic devices^{1, 2}. However, the small effective area of exfoliated MoS₂ has severely limited its practical applications, particularly for tuning optical properties via gate modulation. To address this challenge, we developed a gate-tunable emitter using scalable MoS₂ to enable large-area emission modulation³. High-quality hafnium nitride (HfN) thin films with a work function of 4.65 eV were deposited using high-vacuum magnetron sputtering to achieve optimal work function alignment with monolayer MoS₂.
Photoluminescence (PL) spectra from MoS₂/Al₂O₃/p⁺Si devices under applied gate voltages (-5 V to 5 V) exhibited minimal emission modulation (~2%). In contrast, devices incorporating HfN (MoS₂/Al₂O₃/HfN) as the gate electrode demonstrated significantly enhanced PL modulation (~12%) under the same voltage range, attributed to the unique work function and a strong photogating effect induced trion formation⁴. This modulation was accompanied by a substantial wavelength shift exceeding 14 nm. Moreover, the integration of plasmonic nanostructures that enhancing the light-matter interaction, leading to a 46-fold increase in emission intensity from monolayer MoS₂. This gate-tunable emission offers promising applications in wafer-scale, room-temperature devices for visible light communication, dynamic displays, and tunable light sources. Our approach highlights new possibilities for exploring light-matter interaction and advancing the development of next-generation optoelectronic technologies.

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(4) Syong, W.-R.; Fu, J.-H.; Kuo, Y.-H.; Chu, Y.-C.; Hakami, M.; Peng, T.-Y.; Lynch, J.; Jariwala, D.; Tung, V.; Lu, Y.-J. Enhanced photogating gain in scalable MoS₂ plasmonic photodetectors via resonant plasmonic metasurfaces. ACS Nano 2024, 18, 5446-5456.