Silicene, Siloxene, or Silicane? Revealing the Structure and Optical Properties of Silicon Nanosheets Derived from Calcium Disilicide
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 C...
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Published in | Chemistry of materials Vol. 32; no. 2; pp. 795 - 804 |
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Main Authors | , , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Chemical Society
28.01.2020
American Chemical Society (ACS) |
Subjects | |
Online Access | Get full text |
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Summary: | 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 (∼−30 °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 ∼2.5 eV with direct-like behavior and an estimated quantum yield of ∼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. |
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Bibliography: | USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division DGE 1744592; FA9550-17-1-0170; 1847370; AC02-07CH11358; CNS 1726447 IS-J-10,121 |
ISSN: | 0897-4756 1520-5002 |
DOI: | 10.1021/acs.chemmater.9b04180 |