温度调控WSe₂/WS₂异质结层间激子动力学行为研究

Temperature-Modulated Study of the Dynamical Behavior of Excitons in the Interlayer of WSe₂/WS₂ Heterostructures

摘要: 二维材料异质结中的激子包括面内激子、层间激子等，其中，层间激子为玻色子，其凝聚温度由浓度及有效质量决定，因此其长寿命的优点有助于实现高温下的激子凝聚，从而减小电子耗散速率，使得层间激子成为设计低能耗、高效能的微纳电子器件的重要载体。但层间激子较弱的发光效率进一步加深了其探测难度。研究发现，层间激子对温度具有极高的敏感性，因此，基于光致发光光谱，研究了温度对0˚层间扭转角WSe₂/WS₂异质结中层间激子的影响。发现随温度升高，WSe₂/WS₂异质结中层间激子的发光强度降低，当温度升高至145 K时，WSe₂/WS₂异质结的层间激子完全淬灭，并从层间激子复合动力学角度，揭示了温度调控层间激子动力学的机理。

Abstract: The excitons in the heterojunction of two-dimensional materials include in-plane excitons, interlayer excitons, etc. Among them, the interlayer excitons are bosons, whose coalescence temperature is determined by the concentration and the effective mass, and thus their long-lived advantages help to achieve exciton coalescence at high temperatures and thus reduce the electron dissipation rate, which makes the interlayer excitons become an important carrier for the design of micro- and nano-electronic devices with low energy consumption and high efficiency. However, the weak luminescence efficiency of interlayer excitons further deepens the difficulty of their detection. It was found that the interlayer excitons are extremely sensitive to temperature, so the effect of temperature on the interlayer excitons in WSe₂/WS₂ heterostructures with 0˚ interlayer twist angle was investigated based on photoluminescence spectroscopy. It is found that the luminescence intensity of the interlayer excitons in the WSe₂/WS₂ heterostructures decreases with increasing temperature, and the interlayer excitons in the WSe₂/WS₂ heterostructures are completely quenched when the temperature is increased to 145 K. The mechanism of temperature-regulated interlayer exciton dynamics is also revealed from the viewpoint of interlayer exciton complex dynamics.