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Sundarapura P, Manzhos S, Ihara M. Clarifying the effects of nanoscale porosity of silicon on the bandgap and alignment: a combined molecular dynamics-density functional tight binding computational study. Phys Chem Chem Phys 2023; 25:14566-14577. [PMID: 37191223 DOI: 10.1039/d3cp00633f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Porous silicon (pSi) has been studied for its applications in solar cells, in particular in silicon-silicon tandem solar cells. It is commonly believed that porosity leads to an expansion of the bandgap due to nano-confinement. Direct confirmation of this proposition has been elusive, as experimental band edge quantification is subject to uncertainties and effects of impurities, while electronic structure calculations on relevant length scales are still outstanding. Passivation of pSi is another factor affecting the band structure. We present a combined force field-density functional tight binding study of the effects of porosity of silicon on its band structure. We thus perform electron structure-level calculations for the first time on length scales (several nm) that are relevant to real pSi, and consider multiple nanoscale geometries (pores, pillars, and craters) with key geometrical features and sizes of real porous Si. We consider the presence of a bulk-like base with a nanostructured top layer. We show that the bandgap expansion is not correlated with the pore size but with the size of the Si framework. Significant band expansion would require features of silicon (as opposed to pore sizes) to be as small as 1 nm, while the nanosizing of pores does not induce gap expansion. We observe a graded junction-like behavior of the band gap as a function of Si feature sizes as one moves from the bulk-like base to the nanoporous top layer.
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Affiliation(s)
- Panus Sundarapura
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro-ku, Tokyo 152-8552, Japan.
| | - Sergei Manzhos
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro-ku, Tokyo 152-8552, Japan.
| | - Manabu Ihara
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro-ku, Tokyo 152-8552, Japan.
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2
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Cho K, Yamada T, Tahara H, Tadano T, Suzuura H, Saruyama M, Sato R, Teranishi T, Kanemitsu Y. Luminescence Fine Structures in Single Lead Halide Perovskite Nanocrystals: Size Dependence of the Exciton-Phonon Coupling. NANO LETTERS 2021; 21:7206-7212. [PMID: 34415169 DOI: 10.1021/acs.nanolett.1c02122] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Lead halide perovskite nanocrystals (NCs) have superior photoluminescence (PL) properties, such as high PL quantum yields and wide PL wavelength tunability, for optoelectronic applications. Here, we report the PL spectra of single formamidinium lead halide perovskite FAPbX3 (X = Br, I) NCs examined by single-dot spectroscopy at low temperature. We found four PL peaks in the low-energy region below the strong exciton PL peak that originate from two longitudinal-optical (LO) phonon replicas of the exciton PL, biexcitons, and charged excitons (trions). The binding energies of the biexcitons and trions become larger as the NCs decrease in size. The LO phonon energies show no size dependence, but the Huang-Rhys factors, which reflect the strength of the exciton-phonon coupling, become larger for smaller NCs. Our findings provide important insights into the exciton properties of perovskite NCs.
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Affiliation(s)
- Kenichi Cho
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Takumi Yamada
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Hirokazu Tahara
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Terumasa Tadano
- National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
| | - Hidekatsu Suzuura
- Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
| | - Masaki Saruyama
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Ryota Sato
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Toshiharu Teranishi
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Yoshihiko Kanemitsu
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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3
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O’Toole L, Kang CW, Fang FZ. Precision micro-milling process: state of the art. ADVANCES IN MANUFACTURING 2021; 9:173-205. [PMID: 34777895 PMCID: PMC8550556 DOI: 10.1007/s40436-020-00323-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 06/11/2020] [Accepted: 08/30/2020] [Indexed: 05/19/2023]
Abstract
Micro-milling is a precision manufacturing process with broad applications across the biomedical, electronics, aerospace, and aeronautical industries owing to its versatility, capability, economy, and efficiency in a wide range of materials. In particular, the micro-milling process is highly suitable for very precise and accurate machining of mold prototypes with high aspect ratios in the microdomain, as well as for rapid micro-texturing and micro-patterning, which will have great importance in the near future in bio-implant manufacturing. This is particularly true for machining of typical difficult-to-machine materials commonly found in both the mold and orthopedic implant industries. However, inherent physical process constraints of machining arise as macro-milling is scaled down to the microdomain. This leads to some physical phenomena during micro-milling such as chip formation, size effect, and process instabilities. These dynamic physical process phenomena are introduced and discussed in detail. It is important to remember that these phenomena have multifactor effects during micro-milling, which must be taken into consideration to maximize the performance of the process. The most recent research on the micro-milling process inputs is discussed in detail from a process output perspective to determine how the process as a whole can be improved. Additionally, newly developed processes that combine conventional micro-milling with other technologies, which have great prospects in reducing the issues related to the physical process phenomena, are also introduced. Finally, the major applications of this versatile precision machining process are discussed with important insights into how the application range may be further broadened.
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Affiliation(s)
- Lorcan O’Toole
- Center of Micro/Nano Manufacturing Technology (MNMT-Dublin), University College Dublin, Dublin 4, Ireland
| | - Cheng-Wei Kang
- Center of Micro/Nano Manufacturing Technology (MNMT-Dublin), University College Dublin, Dublin 4, Ireland
| | - Feng-Zhou Fang
- Center of Micro/Nano Manufacturing Technology (MNMT-Dublin), University College Dublin, Dublin 4, Ireland
- State Key Laboratory of Precision Measuring Technology and Instruments, Center of Micro/Nano Manufacturing Technology (MNMT), Tianjin University, Tianjin, 300072 People’s Republic of China
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4
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Cheng CH, Lin GR. Si-QD Synthesis for Visible Light Emission, Color Conversion, and Optical Switching. MATERIALS 2020; 13:ma13163635. [PMID: 32824466 PMCID: PMC7475964 DOI: 10.3390/ma13163635] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 08/07/2020] [Accepted: 08/12/2020] [Indexed: 01/24/2023]
Abstract
This paper reviews the developing progress on the synthesis of the silicon quantum dots (Si-QDs) via the different methods including electrochemical porous Si, Si ion implantation, and plasma enhanced chemical vapor deposition (PECVD), and exploring their featured applications for light emitting diode (LED), color-converted phosphors, and waveguide switching devices. The characteristic parameters of Si-QD LED via different syntheses are summarized for discussion. At first, the photoluminescence spectra of Si-QD and accompanied defects are analyzed to distinguish from each other. Next, the synthesis of porous Si and the performances of porous Si LED reported from different previous works are compared in detail. Later on, the Si-QD implantation in silicide (SiX) dielectric films developed to solve the instability of porous Si and their electroluminescent performances are also summarized for realizing the effect of host matrix to increase the emission quantum efficiency. As the Si-ion implantation still generates numerous defects in host matrix owing to physical bombardment, the PECVD method has emerged as the main-stream methodology for synthesizing Si-QD in SiX semiconductor or dielectric layer. This method effectively suppresses the structural matrix imperfection so as to enhance the external quantum efficiency of the Si-QD LED. With mature synthesis technology, Si-QD has been comprehensively utilized not only for visible light emission but also for color conversion and optical switching applications in future academia and industry.
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Affiliation(s)
- Chih-Hsien Cheng
- Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan;
- NTU-Tektronix Joint Research Center, National Taiwan University and Tektronix Inc., Taipei 10617, Taiwan
| | - Gong-Ru Lin
- Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan;
- NTU-Tektronix Joint Research Center, National Taiwan University and Tektronix Inc., Taipei 10617, Taiwan
- Correspondence: ; Tel.: +886-2-3366-3700-6519
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5
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Time-dependent plasticity in silicon microbeams mediated by dislocation nucleation. Proc Natl Acad Sci U S A 2020; 117:16864-16871. [PMID: 32611814 DOI: 10.1073/pnas.2002681117] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Understanding deformation mechanisms in silicon is critical for reliable design of miniaturized devices operating at high temperatures. Bulk silicon is brittle, but it becomes ductile at about 540 °C. It creeps (deforms plastically with time) at high temperatures (∼800 °C). However, the effect of small size on ductility and creep of silicon remains elusive. Here, we report that silicon at small scales may deform plastically with time at lower temperatures (400 °C) above a threshold stress. We achieve this stress by bending single-crystal silicon microbeams using an in situ thermomechanical testing stage. Small size, together with bending, localize high stress near the surface of the beam close to the anchor. This localization offers flaw tolerance, allowing ductility to win over fracture. Our combined scanning, transmission electron microscopy, and atomic force microscopy analysis reveals that as the threshold stress is approached, multiple dislocation nucleation sites appear simultaneously from the high-stressed surface of the beam with a uniform spacing of about 200 nm between them. Dislocations then emanate from these sites with time, lowering the stress while bending the beam plastically. This process continues until the effective shear stress drops and dislocation activities stop. A simple mechanistic model is presented to relate dislocation nucleation with plasticity in silicon.
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Dorokhin MV, Gavva VA, Ved' MV, Demina PB, Kuznetsov YM, Erofeeva IV, Nezhdanov AV, Boldin MS, Lantsev EA, Popov AA, Trushin VN, Vikhrova OV, Boryakov AV, Yakimov EB, Tabachkova NY. New functional material: spark plasma sintered Si/SiO 2 nanoparticles – fabrication and properties. RSC Adv 2019; 9:16746-16753. [PMID: 35516405 PMCID: PMC9064410 DOI: 10.1039/c9ra01130g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 05/07/2019] [Indexed: 11/21/2022] Open
Abstract
A bulk nanostructured material based on oxidized silicon nanopowder was fabricated using a spark plasma sintering technique. Structural investigations revealed that this material has the composition of ∼14 nm core Si granules inside an SiO2 shell. Photoluminescence measurements have shown that the emission spectra lie in the energy range of 0.6–1.1 eV, which is not typical of the emissions of the Si/SiO2 nanostructures reported in numerous papers. This result can be explained by the formation of energy states in the bandgap and the participation of these states in both electronic transport and photoluminescence emission. Annealing of the sample leads to a decrease in defect density, which in turn leads to quenching of the 0.6–1.1 eV photoluminescence. In this case ∼1.13 eV inter-band transitions in the Si core start to play a dominant role in radiative recombination. Thus, the possibility of controlling the photoluminescence emission over a broad wavelength range was demonstrated. A bulk nanostructured material based on oxidized silicon nanopowder was fabricated using a spark plasma sintering technique.![]()
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Abhilash MR, Gangadhar A, Krishnegowda J, Chikkamadaiah M, Srikantaswamy S. Hydrothermal synthesis, characterization and enhanced photocatalytic activity and toxicity studies of a rhombohedral Fe2O3nanomaterial. RSC Adv 2019; 9:25158-25169. [PMID: 35528652 PMCID: PMC9069891 DOI: 10.1039/c9ra04978a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 08/02/2019] [Indexed: 11/21/2022] Open
Abstract
The present investigation focuses on the synthesis of metal oxide nanoparticles (MONPs)viaa facile hydrothermal route.
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Affiliation(s)
| | - Akshatha Gangadhar
- Department of Studies in Environmental Science
- University of Mysore
- Mysore 570006
- India
- Centre for Materials Science and Technology
| | - Jagadish Krishnegowda
- Department of Studies in Environmental Science
- University of Mysore
- Mysore 570006
- India
- Centre for Materials Science and Technology
| | | | - Shivanna Srikantaswamy
- Department of Studies in Environmental Science
- University of Mysore
- Mysore 570006
- India
- Centre for Materials Science and Technology
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8
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Wang J, Kumeria T, Bezem MT, Wang J, Sailor MJ. Self-Reporting Photoluminescent Porous Silicon Microparticles for Drug Delivery. ACS APPLIED MATERIALS & INTERFACES 2018; 10:3200-3209. [PMID: 29278488 PMCID: PMC5951298 DOI: 10.1021/acsami.7b09071] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A porous Si (pSi) microparticle-based delivery system is investigated, and the intrinsic luminescence from the particles is employed as a probe to monitor the release of a model protein payload, bovine serum albumin (BSA). The microparticles consist of a core Si skeleton surrounded by a SiO2 shell. Two types of pSi are tested, one with smaller (10 nm) pores and the other with larger (20 nm) pores. The larger pore material yields a higher mass loading of BSA (3 vs 20%). Two different methods are used to load BSA into these nanostructures: the first involves loading by electrostatic physisorption, and the second involves trapping of BSA in the pSi matrix by local precipitation of magnesium silicate. Protein release from the former system is characterized by a burst release, whereas in the latter system, release is controlled by dissolution of the pSi/magnesium silicate matrix. The protein release characteristics are studied under accelerated (0.1 M aqueous KOH, 21 °C) and physiologically relevant (phosphate-buffered saline, pH 7.4, 37 °C) conditions, and the near-infrared photoluminescence signal from the pSi skeleton is monitored as a function of time and correlated with protein release and silicon dissolution. The thickness of the Si core and the SiO2 shell are systematically varied, and it is found that the luminescence signature can be tuned to provide a signal that either scales with protein elution or that changes rapidly near the end of useful life of the delivery system. Although payload release and particle dissolution are not driven by the same mechanism, the correlations between luminescence and payload elution for the various formulations can be used to define design rules for this self-reporting delivery system.
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Affiliation(s)
- Joanna Wang
- Material Science and Engineering Program, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Tushar Kumeria
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
- School of Pharmacy, The University of Queensland, 20 Cornwall Street, Woolloongabba, Queensland 4102, Australia
| | - Maria Teresa Bezem
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5020 Bergen, Norway
| | - Jian Wang
- School of Physics and Electronic Information Engineering, Henan Polytechnic University, Jiaozuo 454000, China
| | - Michael J. Sailor
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
- Corresponding Author:
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9
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Jettanasen J, Preecha P, Kunakonrangsiman I, Karpkird T, Limtrakul J. Study of Colloidal Suspensions of Silicon Nanoparticles: Effect of Surface Oxidation on the Photoluminescence Property. INTERNATIONAL JOURNAL OF NANOSCIENCE 2017. [DOI: 10.1142/s0219581x17500119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Nanosilicon is currently under intensive research owing to its extremely promising properties, particularly in photonics domain. However, the photoluminescence (PL) mechanism of silicon nanocrystal remains unclear. We propose, in this paper, a simple method to investigate the PL properties of silicon nanoparticles by exposing the nanoparticles directly to the solvents. The interaction between the nanoparticles and different solvents allows us to assume that not only the quantum size effect but also the surface defect states play a critical role in the PL mechanism, especially at high energy region. This can be confirmed by the results of Transmission Electron Microscopy, FTIR and Raman Spectroscopy.
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Affiliation(s)
- J. Jettanasen
- Department of Chemistry, Faculty of Science, Kasetsart University, P.O. Box 1011, Chatuchak, Bangkok 10903, Thailand
| | - P. Preecha
- Department of Chemistry, Faculty of Science, Kasetsart University, P.O. Box 1011, Chatuchak, Bangkok 10903, Thailand
| | - I. Kunakonrangsiman
- Department of Chemistry, Faculty of Science, Kasetsart University, P.O. Box 1011, Chatuchak, Bangkok 10903, Thailand
| | - T. Karpkird
- Department of Chemistry, Faculty of Science, Kasetsart University, P.O. Box 1011, Chatuchak, Bangkok 10903, Thailand
| | - J. Limtrakul
- Department of Chemistry, Faculty of Science, Kasetsart University, P.O. Box 1011, Chatuchak, Bangkok 10903, Thailand
- Center of Nanotechnology, Kasetsart University, Chatuchak, Bangkok 10903, Thailand
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10
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Zhao Y, Cui T, Wu T, Jin C, Qiao R, Qian Y, Tong G. Polymorphous ZnO Nanostructures: Zn Polar Surface-Guided Size and Shape Evolution Mechanism and Enhanced Photocatalytic Activity. ChemCatChem 2017. [DOI: 10.1002/cctc.201700135] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Yanting Zhao
- College of Chemistry and Life Sciences; Zhejiang Normal University; 688 Yingbin Road Jinhua P.R. China
| | - Tingting Cui
- College of Chemistry and Life Sciences; Zhejiang Normal University; 688 Yingbin Road Jinhua P.R. China
| | - Tong Wu
- College of Chemistry and Molecular Sciences; Wuhan University; 129 Luoyu Road Wuhan P.R. China
| | - Chen Jin
- College of Chemistry and Life Sciences; Zhejiang Normal University; 688 Yingbin Road Jinhua P.R. China
| | - Ru Qiao
- College of Chemistry and Life Sciences; Zhejiang Normal University; 688 Yingbin Road Jinhua P.R. China
| | - Yao Qian
- College of Chemistry and Life Sciences; Zhejiang Normal University; 688 Yingbin Road Jinhua P.R. China
| | - Guoxiu Tong
- College of Chemistry and Life Sciences; Zhejiang Normal University; 688 Yingbin Road Jinhua P.R. China
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11
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Tepliakov NV, Leonov MY, Baranov AV, Fedorov AV, Rukhlenko ID. Quantum theory of electroabsorption in semiconductor nanocrystals. OPTICS EXPRESS 2016; 24:A52-A57. [PMID: 26832597 DOI: 10.1364/oe.24.000a52] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We develop a simple quantum-mechanical theory of interband absorption by semiconductor nanocrystals exposed to a dc electric field. The theory is based on the model of noninteracting electrons and holes in an infinitely deep quantum well and describes all the major features of electroabsorption, including the Stark effect, the Franz-Keldysh effect, and the field-induced spectral broadening. It is applicable to nanocrystals of different shapes and dimensions (quantum dots, nanorods, and nanoplatelets), and will prove useful in modeling and design of electrooptical devices based on ensembles of semiconductor nanocrystals.
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12
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Han L, Zeman M, Smets AHM. Raman study of laser-induced heating effects in free-standing silicon nanocrystals. NANOSCALE 2015; 7:8389-8397. [PMID: 25805442 DOI: 10.1039/c5nr00468c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This paper demonstrates that free-standing silicon nanocrystals (Si NCs) have significantly different thermal conductivity properties compared to Si NCs embedded in a host matrix. The temperatures of Si NCs under laser illumination have been determined by measuring the ratio of the Anti-Stokes to Stokes intensities of the first order Si-Si transverse optical (TO) phonon mode. It is found that large free-standing Si NCs are easily heated up to ∼953 K by the laser light. The laser heating effects are reversible to a large extent, however the nature of the free-standing Si NCs is slightly modified after intensive illumination. The free-standing Si NCs can even be easily melted when exposed to a well-focused laser beam. Under these conditions, the blackbody radiation of the heated Si NCs starts to compete with the detected Raman signals. A simplified model of the heating effects is proposed to study the size dependence of the heated free-standing Si NCs with increasing laser power. It is concluded that the huge red-shift of the Si-Si TO mode observed under intensive laser illumination originates from laser-induced heating effects. In contrast, under similar illumination conditions Si NCs embedded in matrixes are hardly heated due to better thermal conductivity.
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Affiliation(s)
- Lihao Han
- Photovoltaic Materials and Devices (PVMD) Laboratory, Delft University of Technology, P.O. Box 5031, 2600 GA Delft, The Netherlands.
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13
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Optical and Structural Properties of Si Nanocrystals in SiO2 Films. NANOMATERIALS 2015; 5:614-655. [PMID: 28347028 PMCID: PMC5312899 DOI: 10.3390/nano5020614] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 04/07/2015] [Accepted: 04/10/2015] [Indexed: 11/25/2022]
Abstract
Optical and structural properties of Si nanocrystals (Si-nc) in silica films are described. For the SiOx (x < 2) films annealed above 1000 °C, the Raman signal of Si-nc and the absorption coefficient are proportional to the amount of elemental Si detected by X-ray photoelectron spectroscopy. A good agreement is found between the measured refractive index and the value estimated by using the effective-medium approximation. The extinction coefficient of elemental Si is found to be between the values of crystalline and amorphous Si. Thermal annealing increases the degree of Si crystallization; however, the crystallization and the Si–SiO2 phase separation are not complete after annealing at 1200 °C. The 1.5-eV PL quantum yield increases as the amount of elemental Si decreases; thus, this PL is probably not directly from Si-nc responsible for absorption and detected by Raman spectroscopy. Continuous-wave laser light can produce very high temperatures in the free-standing films, which changes their structural and optical properties. For relatively large laser spots, the center of the laser-annealed area is very transparent and consists of amorphous SiO2. Large Si-nc (up to ~300 nm in diameter) are observed in the ring around the central region. These Si-nc lead to high absorption and they are typically under compressive stress, which is connected with their formation from the liquid phase. By using strongly focused laser beams, the structural changes in the free-standing films can be made in submicron areas.
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14
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Meng X, Deng D. Core-shell Ti@Si coaxial nanorod arrays formed directly on current collectors for lithium-ion batteries. ACS APPLIED MATERIALS & INTERFACES 2015; 7:6867-6874. [PMID: 25749298 DOI: 10.1021/acsami.5b00492] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Silicon is a promising candidate to replace the dominantly used carbon as the anode material for lithium ion batteries (LIBs). Si has the highest theoretical capacity (4200 mA·h/g) and is one of the most abundant elements. Unfortunately, Si has the issues of huge volume variation upon dis/charge cycling and low conductivity, leading to poor cycling and rate performances. Designing special nanostructures and improving conductivity and integration of Si electrodes could dramatically enhance their performance. Here, we introduce a novel strategy to integrate the core-shell nanorod arrays of Ti@Si on Ti foil with good conductivity as an additive-free electrode. The Ti core functions as a stable metallic support for the Si shell and dramatically reduces the diffusion length. The as-prepared core-shell nanorod arrays of Ti@Si on Ti foil, without any postsynthesis treatment, as electrodes demonstrated reversible capacity of 1125 mA·h/g over at least 30 cycles with highly improved Coulombic efficiency.
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Affiliation(s)
- Xinghua Meng
- Department of Chemical Engineering and Materials Science, Wayne State University, 5050 Anthony Wayne Drive, Detroit, Michigan 48202, United States
| | - Da Deng
- Department of Chemical Engineering and Materials Science, Wayne State University, 5050 Anthony Wayne Drive, Detroit, Michigan 48202, United States
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15
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Ratchford D, Yeom J, Long JP, Pehrsson PE. Influence of inhomogeneous porosity on silicon nanowire Raman enhancement and leaky mode modulated photoluminescence. NANOSCALE 2015; 7:4124-4133. [PMID: 25666765 DOI: 10.1039/c4nr06329e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Metal-assisted chemical etching (MACE) offers an inexpensive, massively parallel fabrication process for producing silicon nanowires (SiNWs). These nanowires can possess a degree of porosity depending on etch conditions. Because the porosity is often spatially inhomogeneous, there is a need to better understand its nature if applications exploiting the porosity are to be pursued. Here, the resolution afforded by micro-Raman and micro-photoluminescence (PL) is used to elucidate the effects of porosity heterogeneity on the optical properties of individual SiNWs produced in large arrays with MACE, while also determining the spatial character of the heterogeneity. For highly porous SiNWs, there is a dramatic reduction in Raman signal and an increase in PL near the SiNW tips. PL spectra collected along the SiNW length exhibit peaks due to leaky mode resonances. Analysis of the PL resonance peaks, Raman spectrum line shape, SEM images, and EDS spectra indicate that the SiNWs possess both radial and axial heterogeneity wherein, from base to SiNW tip, the SiNWs comprise a shell of increasingly thick porous Si surrounding a tapering core of bulk Si. This work describes how structural porosity variation shapes SiNW optical properties, which will influence the design of new SiNW-based photonic devices and chemical/biological sensors.
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Affiliation(s)
- Daniel Ratchford
- National Research Council Research Associateship Program, Naval Research Laboratory, Washington, DC 20375, USA
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16
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Hou G, Cheng B, Ding F, Yao M, Cao Y, Hu P, Ma R, Yuan F. Well dispersed silicon nanospheres synthesized by RF thermal plasma treatment and their high thermal conductivity and dielectric constant in polymer nanocomposites. RSC Adv 2015. [DOI: 10.1039/c4ra14212h] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Nanocomposites with high thermal conductivity and large dielectric constant incorporated with Si nanospheres prepared by thermal plasma are reported.
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Affiliation(s)
- Guolin Hou
- State Key Laboratory of Multi-phase Complex Systems
- Institute of Process Engineering
- Chinese Academy of Sciences (CAS)
- China
- University of Chinese Academy of Sciences (UCAS)
| | - Benli Cheng
- School of Metallurgical and Ecological Engineering
- University of Science and Technology Beijing
- Beijing 100083
- China
| | - Fei Ding
- State Key Laboratory of Multi-phase Complex Systems
- Institute of Process Engineering
- Chinese Academy of Sciences (CAS)
- China
| | - Mingshui Yao
- State Key Laboratory of Structural Chemistry
- Fujian Institute of Research on the Structure of Matter
- Chinese Academy of Sciences (CAS)
- Fuzhou
- China
| | - Yuebin Cao
- State Key Laboratory of Multi-phase Complex Systems
- Institute of Process Engineering
- Chinese Academy of Sciences (CAS)
- China
| | - Peng Hu
- State Key Laboratory of Multi-phase Complex Systems
- Institute of Process Engineering
- Chinese Academy of Sciences (CAS)
- China
| | - Ruixin Ma
- School of Metallurgical and Ecological Engineering
- University of Science and Technology Beijing
- Beijing 100083
- China
| | - Fangli Yuan
- State Key Laboratory of Multi-phase Complex Systems
- Institute of Process Engineering
- Chinese Academy of Sciences (CAS)
- China
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17
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Choi YR, Zheng M, Bai F, Liu J, Tok ES, Huang Z, Sow CH. Laser-induced greenish-blue photoluminescence of mesoporous silicon nanowires. Sci Rep 2014; 4:4940. [PMID: 24820533 PMCID: PMC4018655 DOI: 10.1038/srep04940] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 04/09/2014] [Indexed: 11/26/2022] Open
Abstract
Solid silicon nanowires and their luminescent properties have been widely studied, but lesser is known about the optical properties of mesoporous silicon nanowires (mp-SiNWs). In this work, we present a facile method to generate greenish-blue photoluminescence (GB-PL) by fast scanning a focused green laser beam (wavelength of 532 nm) on a close-packed array of mp-SiNWs to carry out photo-induced chemical modification. The threshold of laser power is 5 mW to excite the GB-PL, whose intensity increases with laser power in the range of 5–105 mW. The quenching of GB-PL comes to occur beyond 105 mW. The in-vacuum annealing effectively excites the GB-PL in the pristine mp-SiNWs and enhances the GB-PL of the laser-modified mp-SiNWs. A complex model of the laser-induced surface modification is proposed to account for the laser-power and post-annealing effect. Moreover, the fast scanning of focused laser beam enables us to locally tailor mp-SiNWs en route to a wide variety of micropatterns with different optical functionality, and we demonstrate the feasibility in the application of creating hidden images.
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Affiliation(s)
- Yan-Ru Choi
- 1] Hwa Chong Institution, 661 Bukit Timah Rd., Singapore 269734, Singapore [2]
| | - Minrui Zheng
- 1] Department of Physics, 2 Science Drive 3, National University of Singapore (NUS), Singapore 117542, Singapore [2]
| | - Fan Bai
- 1] Department of Physics, Institute of Advanced Materials, Partner State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University (HKBU), Kowloon Tong, Hong Kong SAR, P. R. China [2]
| | - Junjun Liu
- Department of Physics, Institute of Advanced Materials, Partner State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University (HKBU), Kowloon Tong, Hong Kong SAR, P. R. China
| | - Eng-Soon Tok
- Department of Physics, 2 Science Drive 3, National University of Singapore (NUS), Singapore 117542, Singapore
| | - Zhifeng Huang
- 1] Department of Physics, Institute of Advanced Materials, Partner State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University (HKBU), Kowloon Tong, Hong Kong SAR, P. R. China [2] HKBU Institute of Research and Continuing Education, A211, Virtual University Park Building, South Area Hi-Tech Industrial Park, Shenzhen, Guangdong Province, P. R. China
| | - Chorng-Haur Sow
- Department of Physics, 2 Science Drive 3, National University of Singapore (NUS), Singapore 117542, Singapore
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18
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Imakita K, Kamada T, Fujii M, Aoki K, Mizuhata M, Hayashi S. Terahertz wire grid polarizer fabricated by imprinting porous silicon. OPTICS LETTERS 2013; 38:5067-5070. [PMID: 24281511 DOI: 10.1364/ol.38.005067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A terahertz (THz) wire-grid polarizer is fabricated by imprinting porous Si followed by oblique evaporation of Ag. We demonstrate that it works in a wide frequency region covering from 5 to 18 THz with the extinction ratio of 10 dB. The frequency region is much wider than that of THz wire-grid polarizers fabricated by conventional imprint lithography using organic materials. The result suggests that imprinting of porous Si is a promising fabrication technique to realize low-cost wire-grid polarizers working in the THz region.
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Abstract
Quantum confined silicon nanocrystals (Si-ncs) exhibit intriguing properties due to silicon's indirect bandgap and their highly reactive surfaces. In particular the interplay of quantum confinement with surface effects reveals a complex scenario, which can complicate the interpretation of Si-nc properties and prediction of their corresponding behaviour. At the same time, the complexity and interplay of the different mechanisms in Si-ncs offer great opportunities with characteristics that may not be achievable with other nano-systems. In this context, a variety of carefully surface-engineered Si-ncs are highly desirable both for improving our understanding of Si-nc photo-physics and for their successful integration in application devices. Here we firstly highlight a selection of theoretical efforts and experimental surface engineering approaches and secondly we focus on recent surface engineering results that have utilized novel plasma-liquid interactions.
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Affiliation(s)
- Davide Mariotti
- Nanotechnology & Integrated Bio-Engineering Centre-NIBEC, University of Ulster, UK.
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20
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Gresback R, Murakami Y, Ding Y, Yamada R, Okazaki K, Nozaki T. Optical extinction spectra of silicon nanocrystals: size dependence upon the lowest direct transition. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:1802-1807. [PMID: 23320484 DOI: 10.1021/la3042082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We investigate the size-dependent optical extinction properties of colloidal silicon nanocrystals (Si NCs) from the near infrared (NIR) to the ultraviolet (UV). Experimental results are compared to the Mie solution to Maxwell's equations using the same refractive index as bulk Si to evaluate the deviation from bulk properties. We find that the energy for the lowest direct transition (E(1)) continuously blueshifts from near bulk-like at ~3.4 eV in large NCs (16 nm) to ~3.6 eV for small NCs (3.9 nm), contrary to the Mie solution. The extinction cross-section of NCs on a per atom basis was found to be independent of the NC size, within our experimental resolution. The results suggest that quantum confinement effects strongly influence excitons associated with the E(1) transition.
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Affiliation(s)
- Ryan Gresback
- Department of Mechanical and Control Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan
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21
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Zhu J, Gladden C, Liu N, Cui Y, Zhang X. Nanoporous silicon networks as anodes for lithium ion batteries. Phys Chem Chem Phys 2013. [DOI: 10.1039/c2cp44046f] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Amonkosolpan J, Wolverson D, Goller B, Polisski S, Kovalev D, Rollings M, Grogan MDW, Birks TA. Porous silicon nanocrystals in a silica aerogel matrix. NANOSCALE RESEARCH LETTERS 2012; 7:397. [PMID: 22805684 PMCID: PMC3475076 DOI: 10.1186/1556-276x-7-397] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 07/05/2012] [Indexed: 06/01/2023]
Abstract
Silicon nanoparticles of three types (oxide-terminated silicon nanospheres, micron-sized hydrogen-terminated porous silicon grains and micron-size oxide-terminated porous silicon grains) were incorporated into silica aerogels at the gel preparation stage. Samples with a wide range of concentrations were prepared, resulting in aerogels that were translucent (but weakly coloured) through to completely opaque for visible light over sample thicknesses of several millimetres. The photoluminescence of these composite materials and of silica aerogel without silicon inclusions was studied in vacuum and in the presence of molecular oxygen in order to determine whether there is any evidence for non-radiative energy transfer from the silicon triplet exciton state to molecular oxygen adsorbed at the silicon surface. No sensitivity to oxygen was observed from the nanoparticles which had partially H-terminated surfaces before incorporation, and so we conclude that the silicon surface has become substantially oxidised. Finally, the FTIR and Raman scattering spectra of the composites were studied in order to establish the presence of crystalline silicon; by taking the ratio of intensities of the silicon and aerogel Raman bands, we were able to obtain a quantitative measure of the silicon nanoparticle concentration independent of the degree of optical attenuation.
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Affiliation(s)
| | - Daniel Wolverson
- Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Bernhard Goller
- Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY, UK
- Infineon Technologies AG, Siemensstrasse 2, Villach, 9500, Austria
| | - Sergej Polisski
- Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY, UK
- Department of Energy & Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto, 615-8510, Japan
| | - Dmitry Kovalev
- Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Matthew Rollings
- Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Michael D W Grogan
- Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY, UK
- Department of Electrical and Computer Engineering, Boston University, Boston, MA, 02215, USA
| | - Timothy A Birks
- Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY, UK
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Chen K, Bao Z, Shen J, Wu G, Zhou B, Sandhage KH. Freestanding monolithic silicon aerogels. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm31662e] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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24
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Hamidinezhad H, Wahab Y, Othaman Z, Ismail AK. Au-Catalyzed Silicon Nanoneedles Synthesized from Pure Silane Gas at Various RF Powers on Silicon Substrate by VHF-PECVD. PLASMONICS 2011; 6:791-796. [DOI: 10.1007/s11468-011-9266-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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25
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Posada Y, Balberg I, Fonseca L, Resto O, Weisz S. Diffusion Length Measurements of Minority Carriers in Si-SiO2 Using the Photo-Grating Technique. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-638-f14.44.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractWe have studied the microstructure, the transport and the phototransport properties of the Si crystallites network in Si-SiO2 composites. We have found that in our co-sputtered samples the average crystallite diameter, d, decreases from 40 to 5 nm as the content of the silicon, x, decreases from 80 to 40 volume%, and that the percolation of the network sets is at x ≈ 40 vol%. A simultaneous study of the photoluminescence (PL) shows the, quantum confinement, expected red shift of its peak with increasing d. On the other hand the very strong observed decrease of the PL intensity with x is interpreted here as due to a deconfinement effect that is dominated by the increase in the cluster size of connected Si crystallites. The results suggest that a closed random packing of the Si crystallites will be the preferred network for high intensity electroluminescence.
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Abstract
ABSTRACTWe combine photoluminescence excitation spectroscopy and photoconductivity to extract information about the bandgap and particle size distribution of porous silicon. This allows us to specify the influence of size dispersion and to show that different methods to determine absorption probe different parts of the size distribution.
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27
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Mimura H, Matsumoto T, Kanemitsu Y. Blue and Green Electroluminescence from Porous Materials. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-358-635] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTIn applying porous Si (PS) to color display technology, it is important to fabricate light emitting devices with three primary colors. However, there have been few reports on blue and green electroluminescence (EL), and its mechanism (even the relationship between PL and EL spectra) is unclear. To obtain blue and green EL and to investigate its mechanism, we have formed PS anodized under UV illumination (UV-PS) with green photoluminescence (PL) and porous SiC with blue PL. Consequently, green and blue light emitting devices were successfully fabricated by using these materials. The observed spectra are from 350 to 750 nm with a peak of, 520 nm for ITO / UV-PS junctions and from 300 to 600 nm with a peak of 470 nm for ITO / porous SiC junctions. The EL mechanism is also discussed by reference to experimental results of comparing PL and EL spectra and of investigating the dependence of EL intensity on current.
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28
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Biteen JS, Tchebotareva AL, Polman A, Lewis NS, Atwater HA. Controlled Passivation and Luminescence Blue Shifts of Isolated Silicon Nanocrystals. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-770-i6.2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractWe have performed a comparative study of oxide- and nonoxide-passivated silicon nanocrystals to probe the role of the silicon/oxygen interface in low coverage, non-interacting silicon nanocrystal systems. Ensembles of Si nanocrystals characterized by a narrow distribution and diameters of 2–5 nm were synthesized by ion implantation into SiO2 films followed by a high-temperature anneal in Ar. The nanocrystals were removed from the SiO2 film matrix and deposited on Si substrates using a chemical etch in HF, leaving a hydrogen-terminated surface. A natural oxide layer grows on these surfaces in air. We characterized the morphology of the samples with atomic force microscopy (AFM) and the spectroscopic properties with photoluminescence (PL) and X-Ray photoelectron spectroscopy. We found that the PL energy of Si nanocrystals can be shifted by particle size reduction and hydrogen or oxygen termination. Further, PL peak energy shifts upon etching and oxidation were consistent with the model of Wolkin et al. that proposes that for very small radii, a silicon-oxygen double bond will produce deep interface states which red shift the luminescence.
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29
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Muñoz-Noval A, Sánchez-Vaquero V, Torres-Costa V, Gallach D, Ferro-Llanos V, Serrano JJ, Manso-Silván M, García-Ruiz JP, del Pozo F, Martín-Palma RJ. Hybrid luminescent/magnetic nanostructured porous silicon particles for biomedical applications. JOURNAL OF BIOMEDICAL OPTICS 2011; 16:025002. [PMID: 21361682 DOI: 10.1117/1.3533321] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This work describes a novel process for the fabrication of hybrid nanostructured particles showing intense tunable photoluminescence and a simultaneous ferromagnetic behavior. The fabrication process involves the synthesis of nanostructured porous silicon (NPSi) by chemical anodization of crystalline silicon and subsequent in pore growth of Co nanoparticles by electrochemically-assisted infiltration. Final particles are obtained by subsequent sonication of the Co-infiltrated NPSi layers and conjugation with poly(ethylene glycol) aiming at enhancing their hydrophilic character. These particles respond to magnetic fields, emit light in the visible when excited in the UV range, and internalize into human mesenchymal stem cells with no apoptosis induction. Furthermore, cytotoxicity in in-vitro systems confirms their biocompatibility and the viability of the cells after incorporation of the particles. The hybrid nanostructured particles might represent powerful research tools as cellular trackers or in cellular therapy since they allow combining two or more properties into a single particle.
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Affiliation(s)
- Alvaro Muñoz-Noval
- Universidad Autónoma de Madrid, Centro de Investigaciones Biomédicas en Red: Bioingeniería, Biomateriales y Nanomedicina (CIBER-bbn), Departamento de Física Aplicada, Cantoblanco, Madrid, Spain.
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30
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Chizhik AI, Schmidt T, Chizhik AM, Huisken F, Meixner AJ. Dynamical effects of defect photoluminescence from single SiO2 and Si nanoparticles. ACTA ACUST UNITED AC 2011. [DOI: 10.1016/j.phpro.2011.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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31
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de la Mora MB, del Río JA, Nava R, Tagüeña-Martínez J, Reyes-Esqueda JA, Kavokin A, Faubert J, Lugo JE. Anomalous patterned scattering spectra of one-dimensional porous silicon photonic crystals. OPTICS EXPRESS 2010; 18:22808-22816. [PMID: 21164619 DOI: 10.1364/oe.18.022808] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Far-field secondary emission spectra of one-dimensional periodic photonic structures based on porous silicon show characteristic co-focal rings centered close to the structure plane normal. The rings appear when the frequency of picosecond excitation laser pulses is tuned to the edges of the fourth photonic band gap. They can be clearly distinguished from the typical reflected and transmitted light in the oblique incidence geometry. The rings number is dependent on the excitation frequency and the incidence angle. We explain these anomalous spectral features of porous silicon structures by the spectral filtering of light elastically scattered inside the photonic structure by the narrow photonic bands. The elastic scattering of light due to the photonic disorder in the structure causes the appearance of secondary waves propagating in any direction. But only those waves which fall into the allowed photonic bands penetrate through the whole structure and move through its front or back surfaces. The observed patterned secondary emission is an example of efficient photonic engineering by simple means of multilayer porous silicon structures.
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Affiliation(s)
- M B de la Mora
- Centro de Investigación en Energía, Universidad Nacional Autónoma de México, Temixco, 62580 Morelos, México.
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32
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Wu XL, Xiong SJ, Zhu J, Wang J, Shen JC, Chu PK. Identification of surface structures on 3C-SiC nanocrystals with hydrogen and hydroxyl bonding by photoluminescence. NANO LETTERS 2009; 9:4053-4060. [PMID: 19894694 DOI: 10.1021/nl902226u] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
SiC nanocrystals (NCs) exhibit unique surface chemistry and possess special properties. This provides the opportunity to design suitable surface structures by terminating the surface dangling bonds with different atoms thereby boding well for practical applications. In this article, we report the photoluminescence properties of 3C-SiC NCs in water suspensions with different pH values. Besides a blue band stemming from the quantum confinement effect, the 3C-SiC NCs show an additional photoluminescence band at 510 nm when the excitation wavelengths are longer than 350 nm. Its intensity relative to the blue band increases with the excitation wavelength. The 510 nm band appears only in acidic suspensions but not in alkaline ones. Fourier transform infrared, X-ray photoelectron spectroscopy, and X-ray absorption near-edge structure analyses clearly reveal that the 3C-SiC NCs in the water suspension have Si-H and Si-OH bonds on their surface, implying that water molecules only react with a Si-terminated surface. First-principle calculations suggest that the additional 510 nm band arises from structures induced by H(+) and OH(-) dissociated from water and attached to Si dimers on the modified (001) Si-terminated portion of the NCs. The size requirement is consistent with the observation that the 510 nm band can only be observed when the excitation wavelengths are relatively large, that is, excitation of bigger NCs.
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Affiliation(s)
- X L Wu
- National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
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33
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Lettieri S, Maddalenat P, Odierna LP, Ninno D, La Ferrara V, Di Francia G. Measurements of the nonlinear refractive index of free-standing porous silicon layers at different wavelengths. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/13642810012470] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Affiliation(s)
- S. Lettieri
- a Istituto Nazionale per la Fisica della Materia, Dipartiinento di Scienze Fisiche , Università di Napoli ‘Federico II’, Complesso Universitario di M.te S. Angelo , Via Cintia, I-80126 , Napoli , Italy
| | - P. Maddalenat
- a Istituto Nazionale per la Fisica della Materia, Dipartiinento di Scienze Fisiche , Università di Napoli ‘Federico II’, Complesso Universitario di M.te S. Angelo , Via Cintia, I-80126 , Napoli , Italy
| | - L. P. Odierna
- a Istituto Nazionale per la Fisica della Materia, Dipartiinento di Scienze Fisiche , Università di Napoli ‘Federico II’, Complesso Universitario di M.te S. Angelo , Via Cintia, I-80126 , Napoli , Italy
| | - D. Ninno
- a Istituto Nazionale per la Fisica della Materia, Dipartiinento di Scienze Fisiche , Università di Napoli ‘Federico II’, Complesso Universitario di M.te S. Angelo , Via Cintia, I-80126 , Napoli , Italy
| | - V. La Ferrara
- b Centro Ricerche Fotovoltaiche , Ente Nazionale Energìa Alterniva, Localià Granatello, I-80055 , Portici (Napoli) , Italy
| | - G. Di Francia
- b Centro Ricerche Fotovoltaiche , Ente Nazionale Energìa Alterniva, Localià Granatello, I-80055 , Portici (Napoli) , Italy
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34
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Manickam S, Venkatakrishnan K, Tan B, Venkataramanan V. Study of silicon nanofibrous structure formed by femtosecond laser irradiation in air. OPTICS EXPRESS 2009; 17:13869-13874. [PMID: 19654793 DOI: 10.1364/oe.17.013869] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In this study, we report first time the effect of laser pulse repetition frequency and pulse width of femtosecond laser radiation on silicon nanofibrous structure formation under ambient condition. Surface nanotexture analysis revealed the changes in fibrous structure density and size in respect of laser pulse width and repetition frequency. A phonon confinement model is used to explain the Raman spectra of processed specimens in order to understand the structure details of nanofibrous structure and hence to support the surface nanotexture analysis. The present investigation leads to a conclusion that nanofibrous structure is formed due to the aggregation of silicon nanoparticles and their size is estimated using the confinement model which is in the order of few nanometers.
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Affiliation(s)
- Sivakumar Manickam
- Department of Aerospace Engineering, Ryerson University, Toronto, Ontario, Canada
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35
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Photosensitive self-assembled nanoarchitectures containing surfactant-free Si nanocrystals produced by laser fragmentation in water. Chem Phys Lett 2009. [DOI: 10.1016/j.cplett.2009.07.090] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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36
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Rapid Thermal Annealing of Sputtered Silicon-Rich Oxide/SiO[sub 2] Superlattice Structure. ACTA ACUST UNITED AC 2009. [DOI: 10.1149/1.3074295] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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37
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Tsuda T, Nohira T, Amezawa K, Hachiya K, Hagiwara R, Raz O, Ein-Eli Y. Anodic electrode reaction of p-type silicon in 1-ethyl-3-methylimidazolium fluorohydrogenate room-temperature ionic liquid. Electrochim Acta 2008. [DOI: 10.1016/j.electacta.2007.12.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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38
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39
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Balabay R, Chernonog E. Alteration on the surface of the pore walls of the porous silicon under high temperature ageing: Computer simulation. RADIAT MEAS 2007. [DOI: 10.1016/j.radmeas.2007.02.069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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40
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Britkov OM, Gavrilov SA, Grafutin VI, Kalugin VV, Ilyukhina OV, Myasishcheva GG, Prokop’ev EP, Timoshenkov SP, Funtikov YV. A positron annihilation spectroscopy study of porous silicon. HIGH ENERGY CHEMISTRY 2007. [DOI: 10.1134/s0018143907010109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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41
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Wu XL, Deng ZH, Xue FS, Siu GG, Chu PK. Electronic states and luminescence in higher fullerene/porous Si nanocrystal composites. J Chem Phys 2006; 124:214706. [PMID: 16774430 DOI: 10.1063/1.2202742] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Photoluminescence (PL) measurements have been performed on the nanocomposites of higher fullerene-coupled porous silicon (PS) nanocrystals. For the C70PS and C76(78)PS nanocomposites, the PL spectra show a pinning wavelength at approximately 565 nm and for the C84PS and C94PS nanosystems the pinning wavelength is at approximately 590 nm. The PL pinning property is closely related to the sorts of the coupled fullerenes. A band mixing model of direct and indirect gaps in a nanometer environment consisting of nc-Si core, SiO2 surface layer, and coupled fullerene has been proposed for calculation of electronic states. Good agreement is achieved between the experiments and theory.
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Affiliation(s)
- X L Wu
- National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China.
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43
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Gole JL, Veje E, Egeberg RG, Ferreira da Silva A, Pepe I, Dixon DA. Optical Analysis of the Light Emission from Porous Silicon: A Hybrid Polyatom Surface-Coupled Fluorophor. J Phys Chem B 2006; 110:2064-73. [PMID: 16471784 DOI: 10.1021/jp0555302] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The most extensive data set yet generated correlating photoluminescence excitation (PLE) and photoluminescence (PL) spectra is presented for aged (equilibrated) porous silicon (PS) samples. The observed features, which are temperature independent over the range 10-300 K, show a detailed correlation with the results of photoacoustic spectroscopy (PAS) and with molecular electronic structure calculations. The observed energy level patterns are reproduced in the photoabsorption (PA) of PS films released after the etching of a silicon wafer. It is concluded that the energy level pattern found for the photoluminescing surface of PS results from a structure which is neither uniquely molecule- or bulk-like but represents a hybrid form for which the density of states associated with a polyatomic vibrationally excited surface-bound fluorophor dominates the nature of the observed features which are not those of a semiconductor. These fluorophor features are broadened and shifted to lower excitation energy as a result of the intimate presence of the silicon surface to which the fluorophor is bound. The dominance of the surface-bound fluorophor accounts for the temperature-independent PLE and PL features. The observed spectral features are thus suggested to be the result of a strong synergistic interaction in which the silicon surface influences the location of surface-bound fluorophor excited states whereas the nature of the vibrationally excited surface-bound fluorophor coupling to the silicon surface provides the mechanism for an enhanced vibronic structure dominated interaction and energy transfer. The observed PLE, PL, PAS, and PA measurements are found to be consistent with previous photovoltaic and photoconductivity measurements, correlating well with a surface-bound oxyhydride-like emitter. This study suggests the important role that the overtone structure of a molecule bound to a surface can play as one forms a hybrid system.
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Affiliation(s)
- James L Gole
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA.
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Wu XL, Fan JY, Qiu T, Yang X, Siu GG, Chu PK. Experimental evidence for the quantum confinement effect in 3C-SiC nanocrystallites. PHYSICAL REVIEW LETTERS 2005; 94:026102. [PMID: 15698198 DOI: 10.1103/physrevlett.94.026102] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2004] [Indexed: 05/09/2023]
Abstract
Using electrochemical etching of a polycrystalline 3C-SiC target and subsequent ultrasonic treatment in water solution, we have fabricated suspensions of 3C-SiC nanocrystallites that luminesce. Transmission electron microscope observations show that the 3C-SiC nanocrystallites, which uniformly disperse in water, have sizes in the range of 1-6 nm. Photoluminescence and photoluminescence excitation spectral examinations show clear evidence for the quantum confinement of 3C-SiC nanocrystallites with the emission band maximum ranging from 440 to 560 nm. Tunable, composite polystyrene/SiC film can be made by adding polystyrene to a toluene suspension of the 3C-SiC nanocrystallites and then coating the resulting solution onto a Si wafer.
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Affiliation(s)
- X L Wu
- National Laboratory of Solid State Microstructures & Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
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H-Termination of Nanocrystalline Si:O Films by HF Solution Treatment. E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 2005. [DOI: 10.1380/ejssnt.2005.527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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46
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Zou B, Dai J, Xie S. Carrier density and confined polaron effects in the photoluminescence of fresh and oxidized porous silicon. SURF INTERFACE ANAL 2004. [DOI: 10.1002/sia.1667] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Wu XL, Xiong SJ, Siu GG, Huang GS, Mei YF, Zhang ZY, Deng SS, Tan C. Optical emission from excess Si defect centers in Si nanostructures. PHYSICAL REVIEW LETTERS 2003; 91:157402. [PMID: 14611493 DOI: 10.1103/physrevlett.91.157402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2002] [Indexed: 05/24/2023]
Abstract
Four groups of Si nanostructures with and without beta-SiC nanocrystals were fabricated for clarifying the origin of a blue emission with a double-peak structure at 417 and 436 nm. Spectral analyses and microstructural observations show that the blue emission is related to the existence of excess Si atoms in these Si nanostructures. The energy levels of electrons in Si nanocrystals with vacancy defects formed from the excess Si atoms are calculated and the characteristics of the obtained density of states coincide with the observed double-peak emission. The present work provides a possible mechanism of the blue emission in various Si nanostructures.
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Affiliation(s)
- X L Wu
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
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Ohmukai M, Taniguchi M, Tsutsumi Y. Width of Raman Line from Porous Silicon Independent of Total Charge Consumed During Anodization. INTERNATIONAL JOURNAL OF NANOSCIENCE 2003. [DOI: 10.1142/s0219581x0300105x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We investigated the Raman spectra as a function of the total electric charge consumed in forming porous silicon. It was found that the Raman peak shifted to the lower wave number side as the total electric charge increased. However, the width of the Raman line was insensitive to the total electric charge. It shows the size of nanocrystallites can be widely ranged regardless of the degree of electrochemical reactions during anodization.
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Affiliation(s)
- Masato Ohmukai
- Department of Electrical Engineering, Akashi College of Technology, Akashi, Hyogo 674-8501, Japan
| | - Masaki Taniguchi
- Department of Electrical Engineering, Akashi College of Technology, Akashi, Hyogo 674-8501, Japan
| | - Yasuo Tsutsumi
- Department of Electrical Engineering, Akashi College of Technology, Akashi, Hyogo 674-8501, Japan
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Pan LK, Sun CQ, Tay BK, Chen TP, Li S. Photoluminescence of Si Nanosolids near the Lower End of the Size Limit. J Phys Chem B 2002. [DOI: 10.1021/jp0266805] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- L. K. Pan
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 6397987
| | - C. Q. Sun
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 6397987
| | - B. K. Tay
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 6397987
| | - T. P. Chen
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 6397987
| | - S. Li
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 6397987
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