Band Gap Engineering and Layer-by-Layer Mapping of Selenium-Doped Molybdenum Disulfide
Band Gap Engineering and Layer-by-Layer Mapping of Selenium-Doped Molybdenum Disulfide
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DOI：
10.1021/nl4032296
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发表时间：
2014-02-01
期刊：
影响因子：
10.8
通讯作者：
Ajayan, Pulickel M.
中科院分区：
文献类型：
--
作者：
Gong, Yongji;Liu, Zheng;Ajayan, Pulickel M.
三元二维二硫属化物合金表现出成分调制的电子结构，因此，控制这些化合物的每个单独层内的掺杂剂浓度提供了有效地改变其物理和化学性质的有力工具。当量化和定位每层中的掺杂剂原子时，为了更好地理解和微调所需的特性，主要的挑战出现了。在这里，我们报告的二硫化钼取代掺杂范围广泛的硒浓度的合成，导致超过10%的原子层的光学带隙调制。使用Z-对比成像的化学分析提供了单个MoS 2层中掺杂剂原子分布的直接地图，因此提供了局部光学带隙的测量。此外，在双层结构中，掺杂剂分布逐层成像。这个工作表明，在双层系统中的每一层包含相似的局部Se浓度，随机分布，提供了新的见解的生长机制和合金化行为在二维二硫属元素原子层。研究结果表明，制备均匀、三元、二维、电子性质可调的二硫属元素合金薄膜是可行的。
Ternary two-dimensional dichalcogenide alloys exhibit compositionally modulated electronic structure, and hence, control of dopant concentration within each individual layer of these compounds provides a powerful tool to efficiently modify their physical and chemical properties. The main challenge arises when quantifying and locating the dopant atoms within each layer in order to better understand and fine-tune the desired properties. Here we report the synthesis of molybdenum disulfide substitutionally doped with a broad range of selenium concentrations, resulting in over 10% optical band gap modulations in atomic layers. Chemical analysis using Z-contrast imaging provides direct maps of the dopant atom distribution in individual MoS2 layers and hence a measure of the local optical band gaps. Furthermore, in a bilayer structure, the dopant distribution is imaged layer-by-layer. This. work demonstrates that each layer in the bilayer system contains similar local Se concentrations, randomly distributed, providing new insights into the growth mechanism and alloying behavior in two-dimensional dichalcogenide atomic layers. The results show that growth of uniform, ternary, two-dimensional dichalcogenide alloy films with tunable electronic properties is feasible.