Handa Taketo, Huang Chun-Ying, Li Yiliu, Olsen Nicholas, Chica Daniel G, Xu David D, Sturm Felix, McIver James W, Roy Xavier, Zhu Xiaoyang
Department of Chemistry, Columbia University, New York, NY, USA.
Department of Physics, Columbia University, New York, NY, USA.
Nat Mater. 2025 Apr 1. doi: 10.1038/s41563-025-02201-1.
The exfoliation and stacking of two-dimensional van der Waals crystals have created unprecedented opportunities in the discovery of quantum phases. A major obstacle to the advancement of this field is the limited spectroscopic access due to a mismatch in the sample sizes (10-10 m) and the wavelengths (10-10 m) of electromagnetic radiation relevant to their low-energy excitations. Here we introduce ferroelectric semiconductor NbOI as a two-dimensional van der Waals material capable of operating as a van der Waals terahertz emitter. We demonstrate intense and broadband terahertz generation from NbOI with an optical rectification efficiency that is more than one order of magnitude higher than that of ZnTe, the current standard terahertz emitter. Moreover, this NbOI terahertz emitter can be integrated into van der Waals heterostructures to enable on-chip near-field terahertz spectroscopy of a target van der Waals material and device. Our approach provides a general spectroscopic tool for two-dimensional van der Waals materials and quantum matter.
二维范德华晶体的剥离和堆叠为量子相的发现创造了前所未有的机遇。该领域发展的一个主要障碍是，由于与低能激发相关的电磁辐射的样本尺寸（10-10米）和波长（10-10米）不匹配，光谱探测受到限制。在此，我们引入铁电半导体NbOI作为一种二维范德华材料，它能够作为范德华太赫兹发射器。我们展示了NbOI产生的强烈且宽带的太赫兹辐射，其光整流效率比当前标准太赫兹发射器ZnTe高出一个多数量级。此外，这种NbOI太赫兹发射器可以集成到范德华异质结构中，以实现对目标范德华材料和器件的片上近场太赫兹光谱分析。我们的方法为二维范德华材料和量子物质提供了一种通用的光谱工具。
