AI 中文总结
该研究通过光谱学调控TMD单层MoS$_{2x}$Se$_{2(1-x)}$的激子性质，实现光学带隙、圆偏振度等的连续可调，证明合金工程是调控其激子性质的有效策略。
AI 中文摘要
我们利用光谱学研究了全成分范围的单层MoS$_{2x}$Se$_{2(1-x)}$合金，证明光学带隙可在约0.35 eV范围内连续调控，同时B-A激子分裂系统地减小，与密度泛函理论计算结果一致。变温测量显示，从富硒到富硫合金，平均声子能量逐渐增加，符合简约质量标度模型。偏振分辨光谱进一步表明，在78 K下，圆偏振度从MoSe$_2$中的近零单调增加到MoS$_2$中的约15%，观察到的偏振演化归因于合金诱导的电子结构改变，调控了亮暗激子混合及相关谷去极化。这些发现确立了合金工程是控制TMD单层激子性质的有效策略。
英文摘要
We investigate monolayer MoS$_{2x}$Se$_{2(1-x)}$ alloys across the full composition range using optical spectroscopy. We demonstrate continuous tuning of the optical gap over $\sim$0.35 eV, accompanied by a systematic reduction of the B--A exciton splitting, in agreement with density functional theory calculations. Temperature-dependent measurements reveal a progressive increase of the average phonon energy from Se-rich to S-rich alloys that follows a simple reduced-mass scaling model. Polarization-resolved spectroscopy further shows a monotonic increase of the circular polarization from nearly zero in MoSe$_2$ to $\sim$15\% in MoS$_2$ at 78 K. The observed evolution of the polarization is attributed to alloy-induced modifications of the electronic structure that modify bright--dark exciton mixing and the associated valley depolarization. These findings establish alloy engineering as an effective strategy for controlling excitonic properties in TMD monolayers.
Comments11 pages, 4 figures
