Ubrig Nicolas, Ponomarev Evgeniy, Zultak Johanna, Domaretskiy Daniil, Zólyomi Viktor, Terry Daniel, Howarth James, Gutiérrez-Lezama Ignacio, Zhukov Alexander, Kudrynskyi Zakhar R, Kovalyuk Zakhar D, Patané Amalia, Taniguchi Takashi, Watanabe Kenji, Gorbachev Roman V, Fal'ko Vladimir I, Morpurgo Alberto F
Department of Quantum Matter Physics, University of Geneva, Geneva, Switzerland.
Group of Applied Physics, University of Geneva, Geneva, Switzerland.
Nat Mater. 2020 Mar;19(3):299-304. doi: 10.1038/s41563-019-0601-3. Epub 2020 Feb 3.
Van der Waals (vdW) interfaces based on 2D materials are promising for optoelectronics, as interlayer transitions between different compounds allow tailoring of the spectral response over a broad range. However, issues such as lattice mismatch or a small misalignment of the constituent layers can drastically suppress electron-photon coupling for these interlayer transitions. Here, we engineered type-II interfaces by assembling atomically thin crystals that have the bottom of the conduction band and the top of the valence band at the Γ point, and thus avoid any momentum mismatch. We found that these van der Waals interfaces exhibit radiative optical transitions irrespective of the lattice constant, the rotational and/or translational alignment of the two layers or whether the constituent materials are direct or indirect gap semiconductors. Being robust and of general validity, our results broaden the scope of future optoelectronics device applications based on two-dimensional materials.
基于二维材料的范德华（vdW）界面在光电子学领域颇具前景，因为不同化合物之间的层间跃迁能够在很宽的范围内调整光谱响应。然而，诸如晶格失配或组成层的微小错位等问题，会极大地抑制这些层间跃迁的电子 - 光子耦合。在此，我们通过组装原子级薄的晶体来构建II型界面，这些晶体在Γ点具有导带底部和价带顶部，从而避免了任何动量失配。我们发现，这些范德华界面呈现出辐射光学跃迁，而与晶格常数、两层的旋转和/或平移排列无关，也与组成材料是直接带隙还是间接带隙半导体无关。我们的结果具有稳健性和普遍有效性，拓宽了基于二维材料的未来光电器件应用范围。
