Influence of the Dispersion of the Size of the Si Nanocrystals on their Emission Spectra

1994 ◽  
Vol 358 ◽  
Author(s):  
J. B. Khurgin ◽  
E. W. Forsythe ◽  
S. I. Kim ◽  
B. S. Sywe ◽  
B. A. Khan ◽  
...  
Keyword(s):  
Systematic Study ◽  
Quantum Confinement ◽  
Emission Spectra ◽  
Emission Peak ◽  
Nanocrystal Size ◽  
Pl Spectra ◽  
Si Nanocrystals ◽  
Average Size ◽  
Size Dispersion ◽  
Confinement Model

ABSTRACTA systematic study of the PL spectra of Si quantum nanocrystals in the SiO2 matrix has been performed. The results have been fitted to a quantum-confinement model that includes the nanocrystal size dispersion rather than a specific size of the nanocrystal. This serves as a strong confirmation of the confinement-induced nature of the PL. It has been shown that if the dispersion is taken into account, the position of the emission peak as well as the PL width can always be correlated with the average size of the nanocrystal.

scholarly journals Estimation of Silicon Nanocrystalline Sizes from Photoluminescence Measurements of RF Co-Sputtered Si/SiO2 Films.

2002 ◽  
Vol 737 ◽  
Author(s):  
A. Ramírez-Porras ◽  
L.F. Fonseca ◽  
O. Resto
Keyword(s):  
Quantum Dots ◽  
Quantum Confinement ◽  
Quantum Wires ◽  
Sio2 Films ◽  
Pl Spectra ◽  
Si Nanocrystals ◽  
Quartz Substrates ◽  
Stochastic Distribution ◽  
Confinement Model

ABSTRACTA stochastic distribution of nanocrystalline sizes model is applied to fit photoluminescence (PL) spectra of luminescent Si nanocrystals in a Si/SiO2 matrix synthesized by RF co-sputtering on the top of quartz substrates. With this method, the PL spectra from a diverse set of samples can be resolved mainly as the sum of two components: a contribution from a gaussian-like distribution of sizes of quantum dots (QD) and a similar component from a distribution of quantum wires (QW). These distributions of sizes and their associated PL energies agree well with the so-called Smart Quantum Confinement model (SQC).

Resonant excitation of Er3+ by the energy transfer from Si nanocrystals

2000 ◽  
Vol 638 ◽  
Author(s):  
Kei Watanabe ◽  
Minoru Fujii ◽  
Shinji Hayashi
Keyword(s):  
Energy Transfer ◽  
Transfer Process ◽  
Quantum Confinement ◽  
Energy Transfer Process ◽  
Exciton Energy ◽  
Si Nanocrystals ◽  
Wide Range ◽  
Exciton Recombination ◽  
Average Size ◽  
Co Doped

AbstractPhotoluminescence (PL) of SiO2 films co-doped with Si nanocrystals (nc-Si) and Er was studied. The average size of nc-Si was changed in a wide range in order to tune the exciton energy of nc-Si to the energy separations between the discrete electronic states of Er3+. PL from exciton recombination in nc-Si and the intra-4f shell transition of Er3+ were observed simultaneously. At low temperatures, periodic features were observed in the PL spectrum of nc-Si. The period agreed well with the optical phonon energy of Si. The appearance of the phonon structures implies that nc-Si which satisfy the energy conservation rule during the energy transfer process can resonantly excite Er3+. The effects of the quantum confinement of excitons in nc-Si on the energy transfer process are discussed.

Photoluminescence Characteristics of HF-Treated Silicon Nanocrystals

1996 ◽  
Vol 452 ◽  
Author(s):  
S. Nozaki ◽  
S. Sato ◽  
H. Ono ◽  
H. Morisaki
Keyword(s):  
Great Increase ◽  
Dangling Bonds ◽  
Porous Si ◽  
Helium Atmosphere ◽  
Pl Spectra ◽  
Si Nanocrystals ◽  
Evaporation Technique ◽  
Pl Intensity ◽  
Average Size ◽  
Gas Evaporation Technique

AbstractSi nanocrystals were deposited in a helium atmosphere by the gas-evaporation technique. Their average size is 3.5 nm, much smaller than those of the Si nanocrystals deposited in an argon atmosphere. The PL spectra of the as-deposited and the HF-treated Si nanocrystals were compared. A great increase in the PL intensity of the HF-treated Si nanocrystals is attributed to the hydrogen passivation of Si surface dangling bonds. A good correlation between the amount of Si-O bonds and the PL intensity suggests that the oxygen-passivation of dangling bonds is required for the red-band PL. The PL spectra of the HF-treated Si nanocrystals resemble those of porous Si and clearly indicate that the HF-treated Si nanocrystals well simulate the porous Si.

scholarly journals Accurate analysis of the size distribution and crystallinity of boron doped Si nanocrystals via Raman and PL spectra

RSC Advances ◽  
2017 ◽  
Vol 7 (54) ◽  
pp. 34244-34250 ◽  
Author(s):  
X. Jia ◽  
Z. Lin ◽  
T. Zhang ◽  
B. Puthen-Veettil ◽  
T. Yang ◽  
...  
Keyword(s):  
Size Distribution ◽  
Nanocrystal Size ◽  
Size Distributions ◽  
Accurate Analysis ◽  
Pl Spectra ◽  
Boron Doped ◽  
Si Nanocrystals ◽  
Si Nanocrystal

Through fitting of Raman and PL spectra, Si nanocrystal size distributions and Si crystalline fractions are obtained.

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.

Formation of Luminescent Si Nanocrystals by High-Temperature Annealing of Ion-Beam-Sputtered Si/SiO2 Multilayers

2003 ◽  
Vol 775 ◽  
Author(s):  
Suk-Ho Choi ◽  
Jun Sung Bae ◽  
Kyung Jung Kim ◽  
Dae Won Moon
Keyword(s):  
Quantum Confinement ◽  
Radiative Recombination ◽  
Ion Beam ◽  
Quantum Confinement Effect ◽  
Visible Range ◽  
Ion Beam Sputtering ◽  
Transmission Electron ◽  
Si Nanocrystals ◽  
Beam Sputtering ◽  
Microscopy Images

AbstractSi/SiO2 multilayers (MLs) have been prepared under different deposition temperatures (TS) by ion beam sputtering. The annealing at 1200°C leads to the formation of Si nanocrystals in the Si layer of MLs. The high resolution transmission electron microscopy images clearly demonstrate the existence of Si nanocrystals, which exhibit photoluminescence (PL) in the visible range when TS is ≥ 300°C. This is attributed to well-separation of nanocrystals in the higher-TS samples, which is thought to be a major cause for reducing non-radiative recombination in the interface between Si nanocrystal and surface oxide. The visible PL spectra are enhanced in its intensity and are shifted to higher energy by increasing TS. These PL behaviours are consistent with the quantum confinement effect of Si nanocrystals.

scholarly journals Underwater Holographic Sensor for Plankton Studies In Situ Including Accompanying Measurements

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4863
Author(s):  
Victor Dyomin ◽  
Alexandra Davydova ◽  
Igor Polovtsev ◽  
Alexey Olshukov ◽  
Nikolay Kirillov ◽  
...  
Keyword(s):  
World Ocean ◽  
Field Tests ◽  
Field Measurements ◽  
Measuring Systems ◽  
Water Turbidity ◽  
Background Data ◽  
Average Size ◽  
Size Dispersion

The paper presents an underwater holographic sensor to study marine particles—a miniDHC digital holographic camera, which may be used as part of a hydrobiological probe for accompanying (background) measurements. The results of field measurements of plankton are given and interpreted, their verification is performed. Errors of measurements and classification of plankton particles are estimated. MiniDHC allows measurement of the following set of background data, which is confirmed by field tests: plankton concentration, average size and size dispersion of individuals, particle size distribution, including on major taxa, as well as water turbidity and suspension statistics. Version of constructing measuring systems based on modern carriers of operational oceanography for the purpose of ecological diagnostics of the world ocean using autochthonous plankton are discussed. The results of field measurements of plankton using miniDHC as part of a hydrobiological probe are presented and interpreted, and their verification is carried out. The results of comparing the data on the concentration of individual taxa obtained using miniDHC with the data obtained by the traditional method using plankton catching with a net showed a difference of no more than 23%. The article also contains recommendations for expanding the potential of miniDHC, its purpose indicators, and improving metrological characteristics.

scholarly journals Upconversion Luminescence of Silica–Calcia Nanoparticles Co-doped with Tm3+ and Yb3+ Ions

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 937
Author(s):  
Katarzyna Halubek-Gluchowska ◽  
Damian Szymański ◽  
Thi Ngoc Lam Tran ◽  
Maurizio Ferrari ◽  
Anna Lukowiak
Keyword(s):  
Energy Transfer ◽  
Near Infrared ◽  
Upconversion Luminescence ◽  
Sol Gel ◽  
Emission Spectra ◽  
Transmission Electron ◽  
Characteristic Emission ◽  
Diffraction Patterns ◽  
Size Of Particles ◽  
Average Size

Looking for upconverting biocompatible nanoparticles, we have prepared by the sol–gel method, silica–calcia glass nanopowders doped with different concentration of Tm3+ and Yb3+ ions (Tm3+ from 0.15 mol% up to 0.5 mol% and Yb3+ from 1 mol% up to 4 mol%) and characterized their structure, morphology, and optical properties. X-ray diffraction patterns indicated an amorphous phase of the silica-based glass with partial crystallization of samples with a higher content of lanthanides ions. Transmission electron microscopy images showed that the average size of particles decreased with increasing lanthanides content. The upconversion (UC) emission spectra and fluorescence lifetimes were registered under near infrared excitation (980 nm) at room temperature to study the energy transfer between Yb3+ and Tm3+ at various active ions concentrations. Characteristic emission bands of Tm3+ ions in the range of 350 nm to 850 nm were observed. To understand the mechanism of Yb3+–Tm3+ UC energy transfer in the SiO2–CaO powders, the kinetics of luminescence decays were studied.

Laser Induced Etching for Generation of Si Nanocrystals and Spectroscopic Investigation of Morphology

2005 ◽  
Vol 23 ◽  
pp. 43-46
Author(s):  
H.S. Mavi ◽  
S. Rath ◽  
Arun Shukla
Keyword(s):  
Quantum Confinement ◽  
Silicon Nanocrystals ◽  
Laser Wavelength ◽  
Interconnected Network ◽  
Substrate Type ◽  
Argon Ion Laser ◽  
Si Nanocrystals ◽  
Ion Laser ◽  
Laser Induced Etching ◽  
Argon Ion

Laser-induced etching of silicon is used to generate silicon nanocrystals. The pore structure depends on the substrate type and etching laser wavelength. Porous silicon (PS) samples prepared by Nd:YAG laser (1.16 eV) etching of n-type substrate showed a fairly uniform and highly interconnected network of nearly circular pores separated by thin columnar boundaries, while no circular pits were produced by argon- ion laser (2.41 eV) etching under similar conditions. The size and size distribution of the nanocrystals are investigated by Raman and photoluminescence spectroscopies and analyzed within the framework of quantum confinement models.

scholarly journals Depth-Resolved Microspectroscopy of Porous Silicon Multilayers

1999 ◽  
Vol 588 ◽  
Author(s):  
S. Manotas ◽  
F. Agulló-Rueda ◽  
J. D. Moreno ◽  
R. J. Martín-Palma ◽  
R. Guerrero-Lemus ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Silicon Nanocrystals ◽  
Phonon Frequency ◽  
Lattice Mismatch ◽  
High Porosity ◽  
Phonon Confinement ◽  
Heating Effects ◽  
Average Size ◽  
Good Agreement

AbstractWe have measured micro-photoluminescence (PL) and micro-Raman spectra on the cross section of porous silicon multilayers to sample different layer depths. We find noticeable differences in the spectra of layers with different porosity, as expected from the quantum confinement of electrons and phonons in silicon nanocrystals with different average sizes. The PL emission band gets stronger, blue shifts, and narrows at the high porosity layers. The average size can be estimated from the shift. The Raman phonon band at 520 cm−1 weakens and broadens asymmetrically towards the low energy side. The line shape can be related quantitatively with the average size by the phonon confinement model. To get a good agreement with the model we add a band at around 480 cm−1, which has been attributed to amorphous silicon. We also have to leave as free parameters the bulk silicon phonon frequency and its line width, which depend on temperature and stress. We reduced laser power to eliminate heating effects. Then we use the change of frequency with depth to monitor the stress. At the interface with the substrate we find a compressive stress in excess of 10 kbar, which agrees with the reported lattice mismatch. Finally, average sizes are larger than those estimated from PL.

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