AI 中文总结
本研究通过实验与模拟揭示MoS2xSe2(1-x)合金中无序导致载流子扩散率崩塌，确立输运为评估电子质量的关键指标。
AI 中文摘要
二维半导体中的合金化被广泛用于调控带隙，但其对电荷和能量输运的影响仍知之甚少。在此，我们以MoS2xSe2(1-x)合金为模型体系，研究组分、厚度与无序之间的相互作用。光学跃迁和价带色散随化学计量比和层数连续演化，带隙弯曲可忽略不计，且厚度驱动的重整化随组分变化而衰减。相比之下，光激发载流子的时间分辨空间映射揭示了在中间组分处载流子扩散率出现显著且不对称的崩塌，这无法用有效质量或能带排列的变化来解释，而是源于随机硫族元素替代所产生的局域能量景观中的强实空间涨落。微观模拟重现了实验趋势，并表明无序的特性关键取决于合金化的方向，产生散射势垒或深陷阱位点。这些结果共同表明，TMD合金中的输运受无序物理支配，而平衡态下的常规光学和光电子发射探针对此视而不见。我们的发现将输运确立为电子质量的严格度量，并凸显了TMD合金在层状半导体器件应用中固有的局限性。
英文摘要
Alloying in two dimensional semiconductors is widely used to tune bandgaps, yet its implications for charge and energy transport remain poorly understood. Here, we investigate MoS2xSe2(1-x) alloys as a model system to study the interplay between composition, thickness, and disorder. Optical transitions and valence band dispersions evolve continuously with both stoichiometry and number of layers, with negligible bandgap bowing and a composition dependent attenuation of thickness driven renormalization. In contrast, time resolved spatial mapping of photoexcited carriers reveals a pronounced and asymmetric collapse of carrier diffusivity at intermediate compositions, which cannot be accounted for by changes in effective mass or band alignment, and instead emerges from strong real space fluctuations in the local energetic landscape generated by random chalcogen substitution. Microscopic simulations reproduce the experimental trends and show that the character of disorder depends critically on the direction of alloying, producing either scattering barriers or deep trapping sites. Together, these results demonstrate that transport in TMD alloys is governed by disorder physics, overlooked by conventional optical and photoemission probes at equilibrium. Our findings establish transport as a stringent metric of electronic quality and high-light intrinsic limitations in the usage of TMD alloys for layered semiconductor devices.
