二維半導體過渡金屬二硫屬化物：光-物質相互作用和光器件應用

Abstract

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The search for new materials to replace silicon has taken place, and among the favored candidates are the atomically thin two-dimensional (2D) materials that can easily isolate due to their weak interlayer van der Waals forces. A popular example of these materials is the 2D semiconducting transition metal dichalcogenides (TMDs). The single-layer form of 2D TMDs exhibits direct bandgap, high photoluminescence (PL) quantum efficiency, high exciton oscillator strength, and spin-valley coupling-related properties, making them an excellent platform to investigate interesting optical properties. To date, there are only a handful of researchers who are focusing on the effects of light with orbital angular momentum (OAM) and, to some extent, spin angular momentum (SAM) on the optical and electrical properties of 2D TMDs. Hence, this work takes the opportunity to do further experimental investigation and describe the initially unexplored phenomena arising from this light-matter interaction. In this study, monolayer (ML) molybdenum disulfide (MoS2) – a prototypical 2D TMD – was subjected to interaction with incident light having distinct properties. Consequently, it was observed that an incident elliptically polarized light had induced breaking of the symmetry between the x- and y-components of the in-plane Raman mode (E_2g) intensity, while an impinging light with OAM had caused a selective photoexcitation of the exciton quasiparticles manifested by the blue peak energy shifts of the recorded PL intensity. The effects of light with OAM were further investigated and found to have controlled the photovoltaic properties of a MoS2-channeled photodevice. Such observations imply that light with certain properties may facilitate onto the ML MoS2 additional degrees of freedom useful for data storage, enhanced energy harvesting, and sensing applications.