State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai 200433, China.
Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
Nat Commun. 2017 Jan 6;8:14071. doi: 10.1038/ncomms14071.
Black phosphorus is an infrared layered material. Its bandgap complements other widely studied two-dimensional materials: zero-gap graphene and visible/near-infrared gap transition metal dichalcogenides. Although highly desirable, a comprehensive infrared characterization is still lacking. Here we report a systematic infrared study of mechanically exfoliated few-layer black phosphorus, with thickness ranging from 2 to 15 layers and photon energy spanning from 0.25 to 1.36 eV. Each few-layer black phosphorus exhibits a thickness-dependent unique infrared spectrum with a series of absorption resonances, which reveals the underlying electronic structure evolution and serves as its infrared fingerprints. Surprisingly, unexpected absorption features, which are associated with the forbidden optical transitions, have been observed. Furthermore, we unambiguously demonstrate that controllable uniaxial strain can be used as a convenient and effective approach to tune the electronic structure of few-layer black phosphorus. Our study paves the way for black phosphorus applications in infrared photonics and optoelectronics.
黑磷是一种红外层状材料。其带隙与其他广泛研究的二维材料互补：零带隙石墨烯和可见/近红外隙过渡金属二卤化物。尽管这是非常理想的，但仍缺乏全面的红外特性研究。在这里，我们报告了对机械剥离的少层黑磷的系统红外研究，厚度范围从 2 层到 15 层，光子能量从 0.25 到 1.36eV。每个少层黑磷都表现出与厚度相关的独特红外光谱，具有一系列吸收共振，这揭示了其电子结构的演化，并作为其红外指纹。令人惊讶的是，观察到了与禁戒光学跃迁相关的意外吸收特征。此外，我们明确证明，可控的单轴应变可以作为一种方便有效的方法来调节少层黑磷的电子结构。我们的研究为黑磷在红外光子学和光电子学中的应用铺平了道路。
