AI 中文总结
本研究采用激发能依赖的光致发光激发光谱，探测MoSe₂/WSe₂异质双层中层间激子的非线性相互作用，证实其存在净排斥性激子-激子相互作用，确立了PLE作为相关研究的灵敏方法。
AI 中文摘要
过渡金属二硫化物异质双层中的层间激子具有本征的面外偶极矩，为研究高密度下的激子-激子相互作用提供了平台。本研究采用激发能依赖的光致发光激发（PLE）光谱，探测化学气相沉积法生长的MoSe$_2$/WSe$_2$异质双层中偶极层间激子的非线性响应。在固定激发功率下，通过在层内激子共振范围内调谐激发能，可选择性改变注入到层间激子态的布居数。共振激发使系统进入非线性区域，导致层间激子光致发光饱和，且PLE光谱中层内1s共振出现明显展宽；同时，层间激子发射呈现显著蓝移，在4 K时约达2.5 meV，75 K时约达1 meV。该蓝移随层间激子布居数系统性增加，与净排斥性激子-激子相互作用一致，在研究的密度范围内包含偶极-偶极排斥的贡献。研究结果确立了PLE作为一种灵敏方法，可用于获取层间激子的非线性高密度区域，并探测范德华异质结构中层间激子的相互作用。
英文摘要
Interlayer excitons in transition-metal dichalcogenide heterobilayers possess intrinsic out-of-plane dipole moments, providing a platform for investigating exciton-exciton interactions at high densities. Here, we use excitation-energy-dependent photoluminescence excitation (PLE) spectroscopy to probe the nonlinear response of dipolar interlayer excitons in chemical vapor deposition-grown MoSe$_2$/WSe$_2$ heterobilayers. By tuning the excitation energy across intralayer exciton resonances at fixed excitation power, we selectively vary the population injected into the interlayer exciton states. Resonant excitation drives the system into a nonlinear regime, leading to saturation of the interlayer exciton photoluminescence and an apparent broadening of the intralayer $1s$ resonances in the PLE spectra. At the same time, the interlayer exciton emission exhibits a pronounced blueshift, reaching approximately 2.5 meV at 4 K and 1 meV at 75 K. The blueshift increases systematically with the interlayer exciton population and is consistent with a net repulsive exciton-exciton interaction, with contributions from dipole-dipole repulsion in the density regime investigated. Our results establish PLE as a sensitive approach for accessing the nonlinear, high-density regime of interlayer excitons and probing their interactions in van der Waals heterostructures.
CommentsMain and supplement
