Silicene, Siloxene, or Silicane? Revealing the Structure and Optical Properties of Silicon Nanosheets Derived from Calcium Disilicide
Silicene, Siloxene, or Silicane? Revealing the Structure and Optical Properties of Silicon Nanosheets Derived from Calcium Disilicide
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DOI：
10.1021/acs.chemmater.9b04180
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发表时间：
2020-01-28
影响因子：
8.6
通讯作者：
Panthani, Matthew G.
中科院分区：
文献类型：
--
作者：
Ryan, Bradley J.;Hanrahan, Michael P.;Panthani, Matthew G.
硅纳米片（Si-NS）最近吸引了相当大的关注，由于其潜在的电子，光电，自旋电子和催化应用的下一代材料。尽管单层Si-NS是在150多年前通过CaSi 2的拓扑脱嵌首次合成的，但在文献中关于这种材料的结构和光学性质缺乏共识。在这里，我们提供了确凿的证据的结构和化学性质的Si-NS的脱嵌的CaSi 2与冷（类似于-30摄氏度）的HCl水溶液和表征其光学性能。我们使用广泛的技术，包括XRD，FTIR，拉曼，固态NMR，SEM，TEM，EDS，XPS，漫反射吸收，稳态光致发光，时间分辨光致发光和热分解;当它们结合在一起时，这些技术能够独特地洞察Si-NS的结构和光学特性。此外，我们支持的实验结果与密度泛函理论（DFT）计算模拟FTIR，拉曼，固态NMR，带间电子跃迁和能带结构。我们确定的硅-NS包括主要是单氢化物终止的屈曲硅单层。我们表征了纳米片的光学性质，发现它们具有类似于2.5 eV的带隙，具有类似于直接的行为，并且估计量子产率类似于9%。鉴于硅的技术重要性，这些结果对于各种光电技术，如荧光粉，发光二极管和CMOS兼容的光子学是令人鼓舞的。我们的研究结果提供了关键的结构和光学特性，以帮助指导研究界将Si-NS集成到光电和量子器件中。
Si-nanosheets (Si-NSs) have recently attracted considerable attention due to their potential as next-generation materials for electronic, optoelectronic, spintronic, and catalytic applications. Even though monolayer Si-NSs were first synthesized over 150 years ago via topotactic deintercalation of CaSi2, there is a lack of consensus within the literature regarding the structure and optical properties of this material. Herein, we provide conclusive evidence of the structural and chemical properties of Si-NSs produced by the deintercalation of CaSi2 with cold (similar to-30 degrees C) aqueous HCl and characterize their optical properties. We use a wide range of techniques, including XRD, FTIR, Raman, solid-state NMR, SEM, TEM, EDS, XPS, diffuse reflectance absorbance, steady-state photoluminescence, time-resolved photoluminescence, and thermal decomposition; when they are combined together, these techniques enable unique insight into the structural and optical properties of the Si-NSs. Additionally, we support the experimental findings with density functional theory (DFT) calculations to simulate FTIR, Raman, solid-state NMR, interband electronic transitions, and band structures. We determined that the Si-NSs consist of buckled Si monolayers that are primarily monohydride terminated. We characterize the nanosheet optical properties, finding they have a band gap of similar to 2.5 eV with direct-like behavior and an estimated quantum yield of similar to 9%. Given the technological importance of Si, these results are encouraging for a variety of optoelectronic technologies, such as phosphors, light-emitting diodes, and CMOS-compatible photonics. Our results provide critical structural and optical properties to help guide the research community in integrating Si-NSs into optoelectronic and quantum devices.