2 research outputs found

    Observation of Charge Transfer in Heterostructures Composed of MoSe<sub>2</sub> Quantum Dots and a Monolayer of MoS<sub>2</sub> or WSe<sub>2</sub>

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    Monolayer transition metal dichalcogenides (TMDs) are atomically thin semiconductor films that are ideal platforms for the study and engineering of quantum heterostructures for optoelectronic applications. We present a simple method for the fabrication of TMD heterostructures containing MoSe<sub>2</sub> quantum dots (QDs) and a MoS<sub>2</sub> or WSe<sub>2</sub> monolayer. The strong modification of photoluminescence and Raman spectra that includes the quenching of MoSe<sub>2</sub> QDs and the varied spectral weights of trions for the MoS<sub>2</sub> and WSe<sub>2</sub> monolayers were observed, suggesting the charge transfer occurring in these TMD heterostructures. Such optically active heterostructures, which can be conveniently fabricated by dispersing TMD QDs onto TMD monolayers, are likely to have various nanophotonic applications because of their versatile and controllable properties

    Simple Chemical Treatment to n‑Dope Transition-Metal Dichalcogenides and Enhance the Optical and Electrical Characteristics

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    The optical and electrical properties of monolayer transition-metal dichalcogenides (1L-TMDs) are critically influenced by two dimensionally confined exciton complexes. Although extensive studies on controlling the optical properties of 1L-TMDs through external doping or defect engineering have been carried out, the effects of excess charges, defects, and the populations of exciton complexes on the light emission of 1L-TMDs are not yet fully understood. Here, we present a simple chemical treatment method for n-dope 1L-TMDs, which also enhances their optical and electrical properties. We show that dipping 1Ls of MoS<sub>2</sub>, WS<sub>2</sub>, and WSe<sub>2</sub>, whether exfoliated or grown by chemical vapor deposition, into methanol for several hours can increase the electron density and also can reduce the defects, resulting in the enhancement of their photoluminescence, light absorption, and the carrier mobility. This methanol treatment was effective for both n- and p-type 1L-TMDs, suggesting that the surface restructuring around structural defects by methanol is responsible for the enhancement of optical and electrical characteristics. Our results have revealed a simple process for external doping that can enhance both the optical and electrical properties of 1L-TMDs and help us understand how the exciton emission in 1L-TMDs can be modulated by chemical treatments
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