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Surdo S, Barillaro G. Voltage- and Metal-assisted Chemical Etching of Micro and Nano Structures in Silicon: A Comprehensive Review. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2400499. [PMID: 38644330 DOI: 10.1002/smll.202400499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/12/2024] [Indexed: 04/23/2024]
Abstract
Sculpting silicon at the micro and nano scales has been game-changing to mold bulk silicon properties and expand, in turn, applications of silicon beyond electronics, namely, in photonics, sensing, medicine, and mechanics, to cite a few. Voltage- and metal-assisted chemical etching (ECE and MaCE, respectively) of silicon in acidic electrolytes have emerged over other micro and nanostructuring technologies thanks to their unique etching features. ECE and MaCE have enabled the fabrication of novel structures and devices not achievable otherwise, complementing those feasible with the deep reactive ion etching (DRIE) technology, the gold standard in silicon machining. Here, a comprehensive review of ECE and MaCE for silicon micro and nano machining is provided. The chemistry and physics ruling the dissolution of silicon are dissected and similarities and differences between ECE and MaCE are discussed showing that they are the two sides of the same coin. The processes governing the anisotropic etching of designed silicon micro and nanostructures are analyzed, and the modulation of etching profile over depth is discussed. The preparation of micro- and nanostructures with tailored optical, mechanical, and thermo(electrical) properties is then addressed, and their applications in photonics, (bio)sensing, (nano)medicine, and micromechanical systems are surveyed. Eventually, ECE and MaCE are benchmarked against DRIE, and future perspectives are highlighted.
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Affiliation(s)
- Salvatore Surdo
- Dipartimento di Ingegneria dell'Informazione, Università di Pisa, via G. Caruso 16, Pisa, 56122, Italy
| | - Giuseppe Barillaro
- Dipartimento di Ingegneria dell'Informazione, Università di Pisa, via G. Caruso 16, Pisa, 56122, Italy
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Liu J, Yan Y, Zhang Z, Liu Y, Ge J, Guan Z. A Simple Method for the Fabrication of Silicon Inverted Pyramid Substrates for Surface-Enhanced Raman Spectroscopy. MATERIALS (BASEL, SWITZERLAND) 2023; 16:ma16103634. [PMID: 37241262 DOI: 10.3390/ma16103634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 05/06/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023]
Abstract
Silicon inverted pyramids have been shown to exhibit superior SERS properties compared to ortho-pyramids, yet low-cost, simple preparation processes are lacking at present. This study demonstrates a simple method, silver-assisted chemical etching combined with PVP, to construct silicon inverted pyramids with a uniform size distribution. Two types of Si substrates for surface-enhanced Raman spectroscopy (SERS) were prepared via silver nanoparticles deposited on the silicon inverted pyramids by electroless deposition and radiofrequency sputtering, respectively. The experiments were conducted using rhodamine 6G (R6G), methylene blue (MB) and amoxicillin (AMX) molecules to test the SERS properties of the Si substrates with inverted pyramids. The results indicate that the SERS substrates show high sensitivity to detect the above molecules. In particular, the sensitivity and reproducibility of the SERS substrates with a denser silver nanoparticle distribution, prepared by radiofrequency sputtering, are significantly higher than those of the electroless deposited substrates to detect R6G molecules. This study sheds light on a potential low-cost and stable method for preparing silicon inverted pyramids, which is expected to replace the costly commercial Klarite SERS substrates.
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Affiliation(s)
- Jia Liu
- College of Materials Science and Engineering, Nanjing Tech University, 30 South PuZhu Road, Nanjing 210009, China
| | - Yao Yan
- College of Materials Science and Engineering, Nanjing Tech University, 30 South PuZhu Road, Nanjing 210009, China
| | - Zimu Zhang
- College of Materials Science and Engineering, Nanjing Tech University, 30 South PuZhu Road, Nanjing 210009, China
| | - Yuchen Liu
- College of Materials Science and Engineering, Nanjing Tech University, 30 South PuZhu Road, Nanjing 210009, China
| | - Jia Ge
- College of Materials Science and Engineering, Nanjing Tech University, 30 South PuZhu Road, Nanjing 210009, China
| | - Zisheng Guan
- College of Materials Science and Engineering, Nanjing Tech University, 30 South PuZhu Road, Nanjing 210009, China
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Daoudi K, Columbus S, Falcão BP, Pereira RN, Peripolli SB, Ramachandran K, Hadj Kacem H, Allagui A, Gaidi M. Label-free DNA detection using silver nanoprism decorated silicon nanoparticles: Effect of silicon nanoparticle size and doping levels. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 290:122262. [PMID: 36577246 DOI: 10.1016/j.saa.2022.122262] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 11/26/2022] [Accepted: 12/16/2022] [Indexed: 06/17/2023]
Abstract
In the present work, we have fabricated silver nanoprism (AgNPrs)/silicon nanoparticle (SiNPs) hybrid arrays for highly sensitive detection of biomolecules via surface-enhanced Raman spectroscopy (SERS) technique. SiNPs having 7 to 37 nm in size and with phosphorous doping varying from 1 × 1019 to 1 × 1020 cm-3 were synthesized in nonthermal plasma synthesis. SiNPs were further immobilized on glass substrates using spin-coating, followed by deposition of AgNPrs using the drop-casting method. SERS studies showed that AgNPrs/SiNPs hybrid arrays exhibit substantial amplification of fingerprint bands of rhodamine 6G (R6G) compared to bare silicon as the reference. Raman signal intensity was found to be dependent on the size of SiNPs, with the largest nanoparticles exhibiting the highest SERS enhancement. In addition, an increase in phosphorous doping concentration was found to reduce R6G peak intensities. AgNPrs/SiNPs hybrid arrays showed excellent stability over time and high spot-to-spot reproducibility as well. Moreover, hybrid arrays enabled DNA detection through intense vibrational modes of human genomic DNA, with a lower detection limit of 1.5 pg/µL; indicating that AgNPrs/SiNPs sensors can serve as a reliable and cost-effective biosensing platform for rapid and label-free analysis of biomolecules.
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Affiliation(s)
- Kais Daoudi
- Centre for Advanced Materials Research, Research Institute of Sciences and Engineering, University of Sharjah, PO Box 27272, Sharjah, United Arab Emirates; Department of Applied Physics and Astronomy, College of Sciences, University of Sharjah, PO Box 27272, Sharjah, United Arab Emirates.
| | - Soumya Columbus
- Centre for Advanced Materials Research, Research Institute of Sciences and Engineering, University of Sharjah, PO Box 27272, Sharjah, United Arab Emirates
| | - Bruno P Falcão
- CICECO, Department of Physics, University of Aveiro, 3810-193 Aveiro, Portugal; Department of Physics and I3N, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Rui N Pereira
- Department of Physics and I3N, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Suzana B Peripolli
- CICECO, Department of Materials and Ceramic Engineering, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Krithikadevi Ramachandran
- Centre for Advanced Materials Research, Research Institute of Sciences and Engineering, University of Sharjah, PO Box 27272, Sharjah, United Arab Emirates
| | - Hassen Hadj Kacem
- Department of Applied Biology, College of Sciences, University of Sharjah, PO Box 27272, Sharjah, United Arab Emirates
| | - Anis Allagui
- Centre for Advanced Materials Research, Research Institute of Sciences and Engineering, University of Sharjah, PO Box 27272, Sharjah, United Arab Emirates; Department of Sustainable and Renewable Energy Engineering, College of Engineering, University of Sharjah, PO Box 27272, Sharjah, United Arab Emirates
| | - Mounir Gaidi
- Centre for Advanced Materials Research, Research Institute of Sciences and Engineering, University of Sharjah, PO Box 27272, Sharjah, United Arab Emirates; Department of Applied Physics and Astronomy, College of Sciences, University of Sharjah, PO Box 27272, Sharjah, United Arab Emirates; Laboratoire de Photovoltaïque, Centre de Recherches et des Technologies de l'Energie, Technopole de Borj-Cédria, Hammam-Lif 2050, Tunisia
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Kang Y, Kim HJ, Lee SH, Noh H. Paper-Based Substrate for a Surface-Enhanced Raman Spectroscopy Biosensing Platform-A Silver/Chitosan Nanocomposite Approach. BIOSENSORS 2022; 12:266. [PMID: 35624567 PMCID: PMC9138243 DOI: 10.3390/bios12050266] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/15/2022] [Accepted: 04/20/2022] [Indexed: 06/15/2023]
Abstract
Paper is a popular platform material in all areas of sensor research due to its porosity, large surface area, and biodegradability, to name but a few. Many paper-based nanocomposites have been reported in the last decade as novel substrates for surface-enhanced Raman spectroscopy (SERS). However, there are still limiting factors, like the low density of hot spots or loss of wettability. Herein, we designed a process to fabricate a silver-chitosan nanocomposite layer on paper celluloses by a layer-by-layer method and pH-triggered chitosan assembly. Under microscopic observation, the resulting material showed a nanoporous structure, and silver nanoparticles were anchored evenly over the nanocomposite layer. In SERS measurement, the detection limit of 4-aminothiophenol was 5.13 ppb. Furthermore, its mechanical property and a strategy toward further biosensing approaches were investigated.
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Affiliation(s)
- Yuri Kang
- Department of Optometry, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Korea; (Y.K.); (H.J.K.)
| | - Hyeok Jung Kim
- Department of Optometry, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Korea; (Y.K.); (H.J.K.)
| | - Sung Hoon Lee
- Corning Technology Center Korea, Corning Precision Materials Co., Ltd., 212 Tangjeong-ro, Asan 31454, Korea
| | - Hyeran Noh
- Department of Optometry, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Korea; (Y.K.); (H.J.K.)
- Convergence Institute of Biomedical Engineering and Biomaterials, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Korea
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Wang G, Yi R, Zhai X, Bian R, Gao Y, Cai D, Liu J, Huang X, Lu G, Li H, Huang W. A flexible SERS-active film for studying the effect of non-metallic nanostructures on Raman enhancement. NANOSCALE 2018; 10:16895-16901. [PMID: 30175361 DOI: 10.1039/c8nr04971h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Since the discovery of surface enhanced Raman scattering (SERS), the choice of SERS-active materials has been limited mainly to metals, especially gold and silver in the visible spectrum. Although non-metals can also be SERS-active by forming nanostructures or composite structures with SERS-active materials, the mechanism behind it is still unclear and there is no perfect technique to study it. In this work, by constructing a SERS structure on a flexible polydimethylsiloxane film, we provide a way to study the effect of non-metallic nanostructures on Raman enhancement by attaching the above film onto flat and nanostructured surfaces. It was found that a nanoporous silicon surface contributes to an additional, up to five times, Raman enhancement. The pore depth and pore size also influence the observed Raman enhancement. These findings will help us not only to understand the mechanism of SERS involving non-metallic nanostructures, but also to design more efficient SERS structures for various applications.
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Affiliation(s)
- Guilin Wang
- Key Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (NanjingTech), 30 South Puzhu Road, Nanjing 211816, China.
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