Schmeink Jennifer, Musytschuk Vladislav, Pollmann Erik, Sleziona Stephan, Maas André, Kratzer Peter, Schleberger Marika
University of Duisburg-Essen, Faculty of Physics and CENIDE, 47057 Duisburg, Germany.
Nanoscale. 2023 Jun 30;15(25):10834-10841. doi: 10.1039/d3nr01978k.
With the study of Janus monolayer transition metal dichalcogenides, in which one of the two chalcogen layers is replaced by another type of chalcogen atom, research on two-dimensional materials is advancing into new areas. Yet only little is known about this new kind of material class, mainly due to the difficult synthesis. In this work, we synthesize MoSSe monolayers from exfoliated samples and compare their Raman signatures with density functional theory calculations of phonon modes that depend in a nontrivial way on doping and strain. With this as a tool, we can infer limits for the possible combinations of strain and doping levels. This reference data can be applied to all MoSSe Janus samples in order to quickly estimate their strain and doping, providing a reliable tool for future work. In order to narrow down the results for our samples further, we analyze the temperature-dependent photoluminescence spectra and time-correlated single-photon counting measurements. The lifetime of Janus MoSSe monolayers exhibits two decay processes with an average total lifetime of 1.57 ns. Moreover, we find a strong trion contribution to the photoluminescence spectra at low temperature which we attribute to excess charge carriers, corroborating our calculations.
随着对Janus单层过渡金属二硫属化物（其中两层硫属元素层中的一层被另一种硫属元素原子取代）的研究，二维材料的研究正在进入新的领域。然而，对于这种新型材料类别，人们所知甚少，这主要是由于合成困难。在这项工作中，我们从剥离的样品中合成了MoSSe单层，并将它们的拉曼特征与声子模式的密度泛函理论计算进行比较，声子模式以一种非平凡的方式依赖于掺杂和应变。以此作为工具，我们可以推断应变和掺杂水平可能组合的限制。该参考数据可应用于所有MoSSe Janus样品，以便快速估计它们的应变和掺杂情况，为未来的工作提供可靠的工具。为了进一步缩小我们样品的结果范围，我们分析了温度相关的光致发光光谱和时间相关的单光子计数测量。Janus MoSSe单层的寿命表现出两个衰减过程，平均总寿命为1.57 ns。此外，我们发现在低温下光致发光光谱中有很强的三重子贡献，我们将其归因于过量的电荷载流子，这证实了我们的计算。
