Sutter Eli, Wang Jia, Sutter Peter
Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States.
Department of Electrical & Computer Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States.
ACS Nano. 2020 Sep 22;14(9):12248-12255. doi: 10.1021/acsnano.0c05978. Epub 2020 Sep 4.
Engineered heterostructures derive distinct properties from materials integration and interface formation. Two-dimensional crystals have been combined to form vertical stacks and lateral heterostuctures with covalent line interfaces. While thicker vertical stacks have been realized, lateral heterostructures from multilayer van der Waals crystals, which could bring the benefits of high-quality interfaces to bulk-like layered materials, have remained much less explored. Here, we demonstrate the integration of anisotropic layered Sn and Ge monosulfides into complex heterostructures with seamless lateral interfaces and tunable vertical design using a two-step growth process. The anisotropic lattice mismatch at the lateral interfaces between GeS and SnS is relaxed dislocations and interfacial alloying. Nanoscale optoelectronic measurements by cathodoluminescence spectroscopy show the characteristic light emission of joined high-quality van der Waals crystals. Spectroscopy across the lateral interface indicates valley-selective luminescence in the bulk SnS component that arises due to anisotropic electron transfer across the interface. The results demonstrate the ability to realize high-quality lateral heterostructures of multilayer van der Waals crystals for diverse applications, , in optoelectronics or valleytronics.
工程异质结构通过材料整合和界面形成获得独特的性质。二维晶体已被组合形成具有共价线界面的垂直堆叠和横向异质结构。虽然已经实现了更厚的垂直堆叠，但多层范德华晶体的横向异质结构，这种结构可以为块状层状材料带来高质量界面的优势，却仍未得到充分探索。在这里，我们展示了通过两步生长过程，将各向异性的层状硫化锡和硫化锗整合到具有无缝横向界面和可调垂直设计的复杂异质结构中。硫化锗和硫化锡之间横向界面处的各向异性晶格失配通过位错和界面合金化得到缓解。通过阴极发光光谱进行的纳米级光电测量显示了连接在一起的高质量范德华晶体的特征发光。横向界面上的光谱表明，由于界面处各向异性的电子转移，块状硫化锡组分中出现了谷选择性发光。结果表明，能够实现用于多种应用（如光电子学或谷电子学）的多层范德华晶体的高质量横向异质结构。
