Many‐Body Complexes in 2D Semiconductors

Abstract

2D semiconductors such as transition metal dichalcogenides (TMDs) and black phosphorus (BP) are currently attracting great attention due to their intrinsic bandgaps and strong excitonic emissions, making them potential candidates for novel optoelectronic applications. Optoelectronic devices fabricated from 2D semiconductors exhibit many-body complexes (exciton, trion, biexciton, etc.) which determine the materials optical and electrical properties. Characterization and manipulation of these complexes have become a reality due to their enhanced binding energies as a direct result from reduced dielectric screening and enhanced Coulomb interactions in the 2D regime. Furthermore, the atomic thickness and extremely large surface-to-volume ratio of 2D semiconductors allow the possibility of modulating their inherent optical, electrical, and optoelectronic properties using a variety of different environmental stimuli. To fully realize the potential functionalities of these many-body complexes in optoelectronics, a comprehensive understanding of their formation mechanism is essential. A topical and concise summary of the recent frontier research progress related to many-body complexes in 2D semiconductors is provided here. Moreover, detailed discussions covering the aspects of fundamental theory, experimental investigations, modulation of properties, and optoelectronic applications are given. Lastly, personal insights into the current challenges and future outlook of many-body complexes in 2D semiconducting materials are presented.

Nonlinear optics of two‐dimensional transition metal dichalcogenides

“…Ideally, the optical nonlinearity can be fully resolved once we know the band structure completely. However, in TMDs system, the many‐body interaction and the excitonic effects are prominent due to the reduced dielectric screening and the increased 2D confinement . Consequently, the many‐body perturbation theory must be employed for the first‐principle calculation, which could result in complexity of the expression of the corrected nonlinear susceptibility and make the calculation impractical .…”

“…However, in TMDs system, the many-body interaction and the excitonic effects are prominent due to the reduced dielectric screening and the increased 2D confinement. 20,[49][50][51] Consequently, the manybody perturbation theory must be employed for the firstprinciple calculation, which could result in complexity of the expression of the corrected nonlinear susceptibility and make the calculation impractical. 46,47 In order to include the excitonic effects in the nonlinearity calculation, several simple approaches were proposed and they give good agreement with the experimental observations.…”

Polaronic Trions at the MoS2/SrTiO3 Interface

“…In the family of 2D materials, semiconducting transition metal dichalcogenides (TMDs) such as MoS 2 , host extraordinary properties owing to their strong Coulomb interaction that gives rise to tightly bound quasiparticles, such as excitons and trions observed in photoluminescence emission (PLE). The trions, in particular, have attracted substantial interest because of their large binding energy (BE) compared to conventional semiconductor quantum wells, allowing strong light emission even at room temperature.…”

An Adaptive Soft Plasmonic Nanosheet Resonator

“…This type of technology can also be combined with low-dimensional materials for future optomechanical devices. [25][26][27][28][29][30][31][32]…”

“…Due to the advanced near field light–matter interaction inside the plasmonic nanosheet, the resonance frequency is adaptive to either incident light intensity or incident wavelength which gives the proposed device a substantially robust and adaptive response. This type of technology can also be combined with low‐dimensional materials for future opto‐mechanical devices …”