Velja Stefan, Krumland Jannis, Cocchi Caterina
Institute of Physics, Carl von Ossietzky Universität Oldenburg, 26129 Oldenburg, Germany.
Department of Physics and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany.
Nanoscale. 2024 Apr 4;16(14):7134-7144. doi: 10.1039/d3nr06261a.
Mechanical deformations, either spontaneously occurring during sample preparation or purposely induced in their nanoscale manipulation, drastically affect the electronic and optical properties of transition metal dichalcogenide monolayers. In this first-principles work based on density-functional theory, we shed light on the interplay among strain, curvature, and electronic structure of MoSe nanowrinkles. We analyze their structural properties highlighting the effects of coexisting local domains of tensile and compressive strain in the same system. By contrasting the band structures of the nanowrinkles against counterparts obtained for flat monolayers subject to the same amount of strain, we clarify that the specific features of the former, such as the moderate variation of the band-gap size and its persisting direct nature, are ruled by curvature rather than strain. The analysis of the wave-function distribution indicates strain-dependent localization of the frontier states in the conduction region while in the valence, the sensitivity to strain is much less pronounced. The discussion about transport properties, based on inspection of the effective masses, reveals excellent perspectives for these systems as active components for (opto)electronic devices.
机械变形，无论是在样品制备过程中自发产生的，还是在纳米尺度操作中有意引入的，都会极大地影响过渡金属二卤化物单层的电子和光学性质。在这项基于密度泛函理论的第一性原理研究中，我们揭示了MoSe纳米皱纹的应变、曲率和电子结构之间的相互作用。我们分析了它们的结构特性，突出了同一系统中拉伸应变和压缩应变共存的局部区域的影响。通过将纳米皱纹的能带结构与相同应变下的平坦单层的能带结构进行对比，我们阐明了前者的特定特征，如带隙大小的适度变化及其持续的直接性质，是由曲率而非应变决定的。波函数分布分析表明，前沿态在导带区域的局域化与应变有关，而在价带中，对应变的敏感性则不那么明显。基于有效质量的考察对输运性质的讨论，揭示了这些系统作为（光）电子器件活性组件的良好前景。
