Kastl Christoph, Koch Roland J, Chen Christopher T, Eichhorn Johanna, Ulstrup Søren, Bostwick Aaron, Jozwiak Chris, Kuykendall Tevye R, Borys Nicholas J, Toma Francesca M, Aloni Shaul, Weber-Bargioni Alexander, Rotenberg Eli, Schwartzberg Adam M
The Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.
Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.
ACS Nano. 2019 Feb 26;13(2):1284-1291. doi: 10.1021/acsnano.8b06574. Epub 2019 Jan 28.
Two-dimensional materials with engineered composition and structure will provide designer materials beyond conventional semiconductors. However, the potentials of defect engineering remain largely untapped, because it hinges on a precise understanding of electronic structure and excitonic properties, which are not yet predictable by theory alone. Here, we utilize correlative, nanoscale photoemission spectroscopy to visualize how local introduction of defects modifies electronic and excitonic properties of two-dimensional materials at the nanoscale. As a model system, we study chemical vapor deposition grown monolayer WS, a prototypical, direct gap, two-dimensional semiconductor. By cross-correlating nanoscale angle-resolved photoemission spectroscopy, core level spectroscopy, and photoluminescence, we unravel how local variations in defect density influence electronic structure, lateral band alignment, and excitonic phenomena in synthetic WS monolayers.
具有工程化组成和结构的二维材料将提供超越传统半导体的定制材料。然而，缺陷工程的潜力在很大程度上尚未被挖掘，因为它依赖于对电子结构和激子特性的精确理解，而这仅靠理论还无法预测。在这里，我们利用相关的纳米级光电子能谱来可视化缺陷的局部引入如何在纳米尺度上改变二维材料的电子和激子特性。作为一个模型系统，我们研究化学气相沉积生长的单层WS₂，一种典型的、直接带隙的二维半导体。通过将纳米级角分辨光电子能谱、芯能级光谱和光致发光进行交叉关联，我们揭示了缺陷密度的局部变化如何影响合成WS₂单层中的电子结构、横向能带排列和激子现象。
