Luminescent Nanometer-Sized Si Crystals Formed in an amorphous Silicon Dioxide Matrk by Ion Implantation and Annealing

1995 ◽  
Vol 388 ◽  
Author(s):  
T.S. Iwayama ◽  
Y. Terao ◽  
A. Kamiya ◽  
M. Takeda ◽  
S. Nakao ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Annealing Time ◽  
Band Gap Energy ◽  
Electron Hole ◽  
Quantum Confinement Effects ◽  
Transmission Electron ◽  
Si Nanocrystals ◽  
Average Size ◽  
Si Ion Implantation ◽  
Hole Recombination

AbstractSi ion implantation followed by thermal annealing has been used to synthesize luminescent nanometer-sized Si crystals in an amorphous Si02 matrix. Transmission electron microscopy indicates the formation of Si nanocrystals by annealing at 1100 °C, and the growth in average size of Si nanocrystals with increasing annealing time. the shape of the emission spectrum of the photoluminescence is found to be independent of both excitation energy and annealing time, while the excitation spectrum of photoluminescence increases as the photon energy increases and its shape depends on annealing time. the results indicate that the photons are absorbed by Si nanocrystals, for which the band-gap energy is modified by the quantum confinement effects, and the emission of photons is not due to direct electron-hole recombination inside Si nanocrystals but is related to defects probably at the interface between Si nanocrystals and Si02.

CeO2/TiO2 Nanotubes Composites: Synthesis, Characterization, and Photocatalytic Properties

2012 ◽  
Vol 583 ◽  
pp. 86-90 ◽  
Author(s):  
Hai Bin Li ◽  
Xin Yong Li ◽  
Yan De Song ◽  
Shu Guang Chen ◽  
Ying Wang ◽  
...  
Keyword(s):  
Diffuse Reflectance Spectroscopy ◽  
Atomic Ratio ◽  
X Ray Diffraction ◽  
Hydrothermal Route ◽  
Electron Hole ◽  
Calcination Process ◽  
X Ray ◽  
Transmission Electron ◽  
Hole Recombination

TiO2nanotubes were prepared via a hydrothermal route. CeO2nanoparticles with diameters around 5nm were loaded onto the surface of TiO2nanotubes via a deposition approach followed by a calcination process. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectroscopy (UV-vis) were applied for the characterization of the as-prepared CeO2/TiO2nanotubes composites. The results show that CeO2particles are highly dispersed on the surface of TiO2nanotubes. The TiO2 nanotubes are modified to response to the visible light due to the combination with CeO2. The CeO2/TiO2nanotubes composites with a CeO2/TiO2atomic ratio of 2.5% show a further improvement on the photocatalytic activity for degradation of Rhodamine B in water. The presence of CeO2improves the light absorption of TiO2nanotubes and inhibits the electron-hole recombination.

Electrical and Structural Properties of MeV Si+ Ion Implantation in Silicon

1995 ◽  
Vol 378 ◽  
Author(s):  
Aditya Agarwal ◽  
S. Koveshnikov ◽  
K. Christensen ◽  
G. A. Rozgonyi
Keyword(s):  
Ion Implantation ◽  
Deep Level ◽  
Structural Defects ◽  
Extended Defects ◽  
Device Layer ◽  
Implantation Damage ◽  
Transmission Electron ◽  
Current Voltage ◽  
Transient Spectroscopy ◽  
Si Ion Implantation

AbstractThe electrical properties of residual MeV ion implantation damage in Si after annealing from 600 to 1100°C for 1 hour have been investigated using Deep Level Transient Spectroscopy, Capaciatance-Voltage, and Current-Voltage measurements. These data have been correlated with structural defects imaged by Transmission Electron Microscopy. It is shown that at least 4 deep levels are associated with the buried layer of extended defects after annealing at 800, 900, 1000 and 1100°C. Additionally, for the wafer annealed at 800°C at least 5 more deep level centers are present in the device layer above the buried defects.

TEM study of CdS nanocrystals formed in SiO2 by ion implantation

1996 ◽  
Vol 54 ◽  
pp. 236-237
Author(s):  
Jane G. Zhu ◽  
C. W. White ◽  
J. D. Budai ◽  
S. P. Withrow
Keyword(s):  
Ion Implantation ◽  
Electronic Device ◽  
Semiconductor Nanocrystals ◽  
Optical Nonlinearity ◽  
Silicon Substrates ◽  
Cds Nanocrystals ◽  
Quantum Confinement Effects ◽  
Transmission Electron ◽  
Device Applications ◽  
Ion Profiles

Quantum confinement effects and enhanced optical nonlinearity are expected from II-VI semiconductor nanocrystals, which are important for novel opto-electronic device applications. The ion implantation method has been used in our study to form CdS nanocrystals inside amorphous SiO2. The CdS nanocrystals were studied by transmission electron microscopy (TEM).The samples were implanted (at room temperature) with equal doses (1×1017 ions/cm2) of Cd and S into a SiO2 layer on (100) silicon substrates and then annealed under Ar + 4%H2 ambient at 800°C and 1000°C for 1 h. Implant energies were chosen to overlap the Cd and S ion profiles in the middle of the oxide layer. CdS precipitates are formed during the thermal annealing.The effect of annealing temperatures on the nanocrystals size distributions are revealed in Figs. 1 and 2. The sizes of CdS nanocrystals are in the range of 2 - 11 nm for the sample annealed at 800°C, and in the range of a few to 16 nm for the sample annealed at 1000°C.

scholarly journals Influence of nanocrystal size on optical properties of Si nanocrystals embedded in SiO2 synthesized by Si ion implantation

2007 ◽  
Vol 101 (10) ◽  
pp. 103525 ◽  
Author(s):  
L. Ding ◽  
T. P. Chen ◽  
Y. Liu ◽  
M. Yang ◽  
J. I. Wong ◽  
...  
Keyword(s):  
Optical Properties ◽  
Ion Implantation ◽  
Nanocrystal Size ◽  
Si Nanocrystals ◽  
Si Ion Implantation

scholarly journals Synthesis of Heterostructure of ZnO@MOF-46(Zn) to Improve the Photocatalytic Performance in Methylene Blue Degradation

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1379
Author(s):  
Jiraporn Buasakun ◽  
Phakinee Srilaoong ◽  
Ramida Rattanakam ◽  
Tanwawan Duangthongyou
Keyword(s):  
Methylene Blue ◽  
Band Gap ◽  
Photocatalytic Performance ◽  
Degradation Process ◽  
Band Gap Energy ◽  
Photocatalytic Efficiency ◽  
Electron Hole ◽  
Methylene Blue Degradation ◽  
Gap Energy ◽  
Hole Recombination

The heterostructure of ZnO and MOF-46(Zn) was synthesized to improve the photocatalytic performance of ZnO and prove the synergistic theory that presented the coexistence of ZnO and MOF-46(Zn), providing better efficiency than pure ZnO. The heterostructure material was synthesized by using prepared ZnO as a Zn2+ source, which was reacted with 2-aminoterephthalic acid (2-ATP) as a ligand to cover the surface of ZnO with MOF-46(Zn). The ZnO reactant materials were modified by pyrolysis of various morphologies of IRMOF-3 (Zn-MOF) prepared by using CTAB as a morphology controller. The octahedral ZnO obtained at 150 mg of CTAB shows better efficiency for photodegradation, with 85.79% within 3 h and a band gap energy of 3.11 eV. It acts as a starting material for synthesis of ZnO@MOF-46(Zn). The ZnO/MOF-46(Zn) composite was further used as a photocatalyst material in the dye (methylene blue: MB) degradation process, and the performance was compared with that of pure prepared ZnO. The results show that the photocatalytic efficiency with 61.20% in the MB degradation of the heterostructure is higher than that of pure ZnO within 60 min (90.09% within 180 min). The reason for this result may be that the coexistence of ZnO and MOF-46(Zn) can absorb a larger range of energy and reduce the possibility of the electron–hole recombination process.

scholarly journals Simple Synthesis and Luminescence Characteristics of PVP-Capped GeO2Nanoparticles

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Wei Wu ◽  
Xu Zou ◽  
Quanjun Li ◽  
Bingbing Liu ◽  
Bo Liu ◽  
...  
Keyword(s):  
Surface Defects ◽  
Hydrothermal Process ◽  
Thermo Gravimetric Analysis ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
Transmission Electron ◽  
Luminescence Characteristics ◽  
Facile Hydrothermal Process ◽  
Hole Recombination

Polyvinylpyrrolidone (PVP)-capped rutile GeO2nanoparticles were synthesized through a facile hydrothermal process. The obtained nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), and photoluminescence spectroscopy (PL). The capped GeO2nanoparticles showed significantly enhanced luminescence properties compared with those of the uncapped ones. We attributed this result to the effect of reducing surface defects and enhancing the possibility of electron-hole recombination of the GeO2nanoparticles by the PVP molecules. PVP-capped GeO2nanoparticles have potential application in optical and electronic fields.

scholarly journals Electrospun Active Media Based on Polyvinylidene Fluoride (PVDF)-Graphene-TiO2 Nanocomposite Materials for Methanol and Acetaldehyde Gas-Phase Abatement

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1017
Author(s):  
Carlo Boaretti ◽  
Giuseppe Vitiello ◽  
Giuseppina Luciani ◽  
Alessandra Lorenzetti ◽  
Michele Modesti ◽  
...  
Keyword(s):  
Gas Phase ◽  
Polyvinylidene Fluoride ◽  
Indoor Air Pollution ◽  
Uv Light ◽  
Band Gap Energy ◽  
Electron Hole ◽  
Volatile Organic ◽  
High Concern ◽  
Nanostructured Membranes ◽  
Hole Recombination

The abatement of organic pollutants by TiO2 photocatalysis has been established as one of the benchmark applications of advanced oxidation processes for both liquid and gas phase purification. Such solution is particularly suitable for indoor air pollution where volatile organic compounds (VOCs) represent a class of chemicals of high concern for their adverse effects on both environment and human health. However, different shortcomings still affects TiO2 photocatalytic performance in terms of weak adsorptivity and fast electron-hole recombination, limiting its applicability. As a result, different strategies have been investigated over the last years in order to promote a higher TiO2 photo-efficiency. In this study we used electrospun (PVDF) nanofibers as a support for the photo catalytic system obtained by coupling graphene based materials and TiO2 during solvothermal synthesis. The resultant nanostructured membranes have been tested for acetaldehyde and methanol degradation under UV light showing an increase in the photocatalytic activity compared to bare TiO2. Such results may be ascribed to the decrease of band-gap energy and to increased electron mobility in the photocatalytic nanocomposite.

Optical Properties of Si Nanoclusters with Passivated Surfaces

1996 ◽  
Vol 431 ◽  
Author(s):  
L. N. Dinh ◽  
L. L. Chase ◽  
M. Balooch ◽  
W. J. Siekhaus ◽  
F. Wooten
Keyword(s):  
Blue Shift ◽  
Buffer Gas ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthesis Conditions ◽  
Pl Spectra ◽  
Transmission Electron ◽  
Si Nanocrystals ◽  
Decay Times ◽  
Average Size

AbstractSi nanoclusters with average size of a few nanometers have been synthesized by thermal vaporization of Si in an Ar buffer gas, and passivated with oxygen or atomic hydrogen. High resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) revealed that these nanoclusters were crystalline. All samples showed strong infrared and/or visible photoluminescence (PL) with varying decay times from nanoseconds to microseconds depending on synthesis conditions. Absorption mainly in the Si cores was observed by photoluminescence excitation (PLE) spectroscopy. The visible components of PL spectra were noted to blue shift and broaden as the size of the Si nanocrystals (nc-Si) was reduced, and there were differences in PL spectra for hydrogen and oxygen passivated nc-Si. Our data can be explained best by a model involving absorption between quantum confined states in the Si cores and emission by surface/interface states.

scholarly journals Oxidation of Si nanocrystals fabricated by ultra-low energy ion implantation in thin SiO2 layers

2004 ◽  
Vol 830 ◽  
Author(s):  
H. Coffin ◽  
C. Bonafos ◽  
S. Schamm ◽  
N. Cherkashin ◽  
M. Respaud ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Structural Characteristics ◽  
Scanning Transmission Electron Microscope ◽  
Chemical Oxidation ◽  
Low Energy ◽  
Annealing Duration ◽  
Spatially Resolved ◽  
Transmission Electron ◽  
Si Nanocrystals ◽  
Scanning Transmission

ABSTRACTThe effect of annealing in diluted oxygen on the structural characteristics of thin silicon dioxide layers with embedded Si nanocrystals fabricated by ultra-low energy ion implantation (1 keV) is reported. The nanocrystal characteristics (size, density, coverage) have been measured by spatially resolved Electron Energy Loss Spectroscopy using the spectrum-imaging mode of a Scanning Transmission Electron Microscope. Their evolution has been studied as a function of the annealing duration under N2+O2 at 900°C. An extended spherical Deal-Grove model for the self-limiting oxidation of embedded silicon nanocrystals has been carried out. It shows that stress effects, due to the deformation of the oxide, slows down the chemical oxidation rate and leads to a self-limiting oxide growth. The model predictions show a good agreement with the experimental results.

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