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Title: Silicene, Siloxene, or Silicane? Revealing the Structure and Optical Properties of Silicon Nanosheets Derived from Calcium Disilicide

Abstract

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 CaSi 2, 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 CaSi 2 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 technologicalmore » importance of Si, these results are encouraging for a variety of optoelectronic technologies, such as phosphors, light-emitting diodes, and CMOS-compatible photonics. Furthermore, our results provide critical structural and optical properties to help guide the research community in integrating Si-NSs into optoelectronic and quantum devices.« less

Authors:
ORCiD logo [1];  [2];  [1];  [1];  [2]; ORCiD logo [1];  [3];  [3];  [4];  [3]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [1]
  1. Iowa State Univ., Ames, IA (United States)
  2. Iowa State Univ., Ames, IA (United States); Ames Lab., Ames, IA (United States)
  3. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
  4. Ames Lab., Ames, IA (United States)
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
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
OSTI Identifier:
1580708
Report Number(s):
IS-J-10,121
Journal ID: ISSN 0897-4756
Grant/Contract Number:  
DGE 1744592; FA9550-17-1-0170; 1847370; AC02-07CH11358; CNS 1726447
Resource Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Name: Chemistry of Materials; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English

Citation Formats

Ryan, Bradley J., Hanrahan, Michael P., Wang, Yujie, Ramesh, Utkarsh, Nyamekye, Charles K. A., Nelson, Rainie D., Liu, Zhaoyu, Huang, Chuankun, Whitehead, Bevan, Wang, Jigang, Roling, Luke T., Smith, Emily A., Rossini, Aaron J., and Panthani, Matthew G. Silicene, Siloxene, or Silicane? Revealing the Structure and Optical Properties of Silicon Nanosheets Derived from Calcium Disilicide. United States: N. p., 2019. Web. doi:10.1021/acs.chemmater.9b04180.
Ryan, Bradley J., Hanrahan, Michael P., Wang, Yujie, Ramesh, Utkarsh, Nyamekye, Charles K. A., Nelson, Rainie D., Liu, Zhaoyu, Huang, Chuankun, Whitehead, Bevan, Wang, Jigang, Roling, Luke T., Smith, Emily A., Rossini, Aaron J., & Panthani, Matthew G. Silicene, Siloxene, or Silicane? Revealing the Structure and Optical Properties of Silicon Nanosheets Derived from Calcium Disilicide. United States. doi:10.1021/acs.chemmater.9b04180.
Ryan, Bradley J., Hanrahan, Michael P., Wang, Yujie, Ramesh, Utkarsh, Nyamekye, Charles K. A., Nelson, Rainie D., Liu, Zhaoyu, Huang, Chuankun, Whitehead, Bevan, Wang, Jigang, Roling, Luke T., Smith, Emily A., Rossini, Aaron J., and Panthani, Matthew G. Tue . "Silicene, Siloxene, or Silicane? Revealing the Structure and Optical Properties of Silicon Nanosheets Derived from Calcium Disilicide". United States. doi:10.1021/acs.chemmater.9b04180.
@article{osti_1580708,
title = {Silicene, Siloxene, or Silicane? Revealing the Structure and Optical Properties of Silicon Nanosheets Derived from Calcium Disilicide},
author = {Ryan, Bradley J. and Hanrahan, Michael P. and Wang, Yujie and Ramesh, Utkarsh and Nyamekye, Charles K. A. and Nelson, Rainie D. and Liu, Zhaoyu and Huang, Chuankun and Whitehead, Bevan and Wang, Jigang and Roling, Luke T. and Smith, Emily A. and Rossini, Aaron J. and Panthani, Matthew G.},
abstractNote = {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. Furthermore, our results provide critical structural and optical properties to help guide the research community in integrating Si-NSs into optoelectronic and quantum devices.},
doi = {10.1021/acs.chemmater.9b04180},
journal = {Chemistry of Materials},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {11}
}

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This content will become publicly available on November 12, 2020
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