CONTINUOUS-WAVE PHOTOLUMINESCENCE AND NANOSTRUCTURAL PROPERTIES OF POROUS SILICON

2009 ◽  
Vol 08 (03) ◽  
pp. 311-318
Author(s):  
ADWAN Al-AJILI
Keyword(s):  
Electron Microscopy ◽  
Porous Silicon ◽  
Continuous Wave ◽  
Structural Information ◽  
Photoluminescence Excitation ◽  
Porous Si ◽  
X Ray ◽  
Diffraction Patterns ◽  
Silicon Based ◽  
X Ray Absorption

The photoluminescence (PL) emitted by porous silicon has been investigated by using the continuous tuneable UV Synchrotron Radiation Source. One sample was investigated for orange PL emission wavelength at temperatures 77–295 K. The PL peak is found to shift to higher frequency with decreasing temperature. Information about the nanostructure of porous silicon has been determined from PL and Extended X-ray Absorption Fine Structure (EXAFS), as well as from electron microscopy. In particular, the optical properties of silicon-based nanostructured materials, obtained from PL and photoluminescence excitation measurements, have been correlated with structural information from Si –K-edge EXAFS. Electron microscopy was used to study the relation between the nanostructure and PL of porous Si , and to investigate porous Si structure. Platelet Si and Si crystallites in porous Si layers were observed. The size of crystallites ranged from 4 to 6.5 nm. Diffraction patterns show these porous Si samples have a crystalline structure.

Light Emission from Porous Silicon Subjected to Rapid Thermal Oxidation

1992 ◽  
Vol 283 ◽  
Author(s):  
A. G. Cullis ◽  
L. T. Canham ◽  
G. M. Williams ◽  
P. W. Smith ◽  
O. D. Dosser
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Porous Silicon ◽  
Light Emission ◽  
Porous Si ◽  
Light Emitting ◽  
X Ray ◽  
Amorphous Phases ◽  
Transmission Electron ◽  
Si Nanostructures

ABSTRACTLuminescent oxidised porous Si is produced by rapid thermal annealing of the anodised material in a dry oxygen ambient. Its light-emitting properties are studied by both photoluminescence and cathodoluminescence methods. The structure of the oxidised material is examined by transmission electron microscopy, while its oxygen content is determined by X-ray microanalysis. These investigations show that crystalline Si nanostructures remain in the oxidised porous material and account for its luminescence properties. The work demonstrates that the speculated importance of either Si-based amorphous phases or the interesting material, siloxene, in this regard is unrealistic.

scholarly journals Homogeneous Incorporation of Gallium into Layered Double Hydroxide Lattice for Potential Radiodiagnostics: Proof-of-Concept

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 44
Author(s):  
Do-Gak Jeung ◽  
Tae-Hyun Kim ◽  
Jae-Min Oh
Keyword(s):  
Electron Microscopy ◽  
Layered Double Hydroxide ◽  
Inductively Coupled Plasma ◽  
Hydrothermal Reaction ◽  
Edge Structure ◽  
X Ray ◽  
Inductively Coupled ◽  
Diffraction Patterns ◽  
Double Hydroxide ◽  
X Ray Absorption

Trivalent gallium ion was successfully incorporated into chemically well-defined MgAl-layered double hydroxide (LDH) frameworks through postsynthetic hydrothermal treatment. Quantitative analysis with inductively coupled plasma-mass spectroscopy exhibited that Ga3+ was first incorporated into LDH through partial dissolution-precipitation at the edge of LDH particle and homogeneously distributed throughout the particle by substitution of Ga3+ for Al3+ in LDH frame works. The powder X-ray diffraction patterns showed that the Ga3+ incorporation did not affect the crystal structure without evolution of unexpected impurities. The morphology and surface property of LDH evaluated by scanning electron microscopy and light scattering showed the preservation of physicochemical properties throughout 24 h of hydrothermal reaction. The distribution of incorporated Ga3+ was visualized with energy dispersive spectroscopy-assisted transmission electron microscopy, suggesting the homogeneous location of Ga3+ in an LDH particle. The X-ray absorption near-edge structure and extended X-ray absorption fine structure suggested that the Ga moiety was immobilized in LDH from 0.5 h and readily crystallized upon reaction time.

Unimportance of Siloxene in Luminescent Porous Silicon as Determined by Nexafs & Exafs

1993 ◽  
Vol 298 ◽  
Author(s):  
S.L. Friedman ◽  
M.A. Marcus ◽  
D.L. Adler ◽  
Y.-H. Xie ◽  
T.D. Harris ◽  
...  
Keyword(s):  
Fine Structure ◽  
Porous Silicon ◽  
Room Temperature ◽  
Emission Spectra ◽  
Porous Si ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption ◽  
Room Temperature Luminescence ◽  
Combined Data

AbstractNear-edge-- and extended--x-ray absorption fine structure measurements, as well as luminescence excitation and emission spectra, were obtained from samples of porous Si and siloxene. Contrary to a recently proposed explanation for the room temperature luminescence in porous Si, the combined data indicate that siloxene is not principally responsible for the observed effect.

scholarly journals Continuous Synthesis of Cu/ZnO/Al2O3 Nanoparticles in a Co-precipitation Reaction Using a Silicon Based Microfluidic Reactor

2022 ◽  
Author(s):  
Ghazal Tofighi ◽  
Henning Lichtenberg ◽  
Abhijeet Gaur ◽  
Wu Wang ◽  
Stefan Wild ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Methanol Synthesis ◽  
Precipitation Reaction ◽  
Al2o3 Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microfluidic Reactor ◽  
Co Precipitation ◽  
Silicon Based ◽  
X Ray Absorption

CuO/ZnO/Al2O3 catalysts were continuously synthesized in a microfluidic reactor, analyzed by X-ray diffraction (XRD), physisorption (BET), chemisorption, electron microscopy and X-ray absorption spectroscopy (XAS), and tested for methanol synthesis from...

Si K-edge X-ray absorption fine structure studies of porous silicon

1992 ◽  
Vol 70 (10-11) ◽  
pp. 813-818 ◽  
Author(s):  
T. K. Sham ◽  
X. H. Feng ◽  
D. T. Jiang ◽  
B. X. Yang ◽  
J. Z. Xiong ◽  
...  
Keyword(s):  
Fine Structure ◽  
Porous Silicon ◽  
Surface Oxygen ◽  
Porous Si ◽  
Oxygen Compound ◽  
X Ray ◽  
Absorption Fine ◽  
Fine Structures ◽  
X Ray Absorption ◽  
Si Wafer

X-ray absorption fine structure (XAFS) spectra of porous Si prepared by the anodization of a Si wafer in aqueous HF solution have been obtained with synchrotron radiation. The Si K-edge near-edge X-ray absorption fine structure and extended X-ray absorption fine structures clearly show that porous silicon samples that have been exposed to the ambient environment (untreated) have an oxide layer, while the "clean" (treated) porous Si sample regenerated by HF treatment shows some degradation in its crystallinity. Noticeable differences in the XAFS between porous Si and crystalline Si are noted. The results and implications of this observation and the chemistry leading to the formation of surface oxygen compound are discussed.

scholarly journals Effects in the Optical and Structural Properties Caused by Mg or Zn Doping of GaN Films Grown via Radio-Frequency Magnetron Sputtering Using Laboratory-Prepared Targets

2021 ◽  
Vol 11 (15) ◽  
pp. 6990
Author(s):  
Erick Gastellóu ◽  
Godofredo García ◽  
Ana María Herrera ◽  
Crisoforo Morales ◽  
Rafael García ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Magnetron Sputtering ◽  
Radio Frequency ◽  
Hexagonal Structure ◽  
Binding Energies ◽  
Radio Frequency Magnetron ◽  
Radio Frequency Magnetron Sputtering ◽  
X Ray ◽  
Diffraction Patterns ◽  
Mg Doped

GaN films doped with Mg or Zn were obtained via radio-frequency magnetron sputtering on silicon substrates at room temperature and used laboratory-prepared targets with Mg-doped or Zn-doped GaN powders. X-ray diffraction patterns showed broadening peaks, which could have been related to the appearance of nano-crystallites with an average of 7 nm. Scanning electron microscopy and transmission electron microscopy showed good adherence to silicon non-native substrate, as well as homogeneity, with a grain size average of 0.14 µm, and 0.16 µm for the GaN films doped with Zn or Mg, respectively. X-ray photo-electron spectroscopy demonstrated the presence of a very small amount of magnesium (2.10 mol%), and zinc (1.15 mol%) with binding energies of 1303.18, and 1024.76 eV, respectively. Photoluminescence spectrum for the Zn-doped GaN films had an emission range from 2.89 to 3.0 eV (429.23–413.50 nm), while Mg-doped GaN films had an energy emission in a blue-violet band with a range from 2.80 to 3.16 eV (443.03–392.56 nm). Raman spectra showed the classical vibration modes A1(TO), E1(TO), and E2(High) for the hexagonal structure of GaN.

Determining the C60 molecular arrangement in thin films by means of X-ray diffraction

2011 ◽  
Vol 44 (5) ◽  
pp. 983-990 ◽  
Author(s):  
Chris Elschner ◽  
Alexandr A. Levin ◽  
Lutz Wilde ◽  
Jörg Grenzer ◽  
Christian Schroer ◽  
...  
Keyword(s):  
Thin Films ◽  
Structural Information ◽  
Grazing Incidence ◽  
Test Material ◽  
C60 Fullerene ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molecular Arrangement ◽  
Diffraction Patterns

The electrical and optical properties of molecular thin films are widely used, for instance in organic electronics, and depend strongly on the molecular arrangement of the organic layers. It is shown here how atomic structural information can be obtained from molecular films without further knowledge of the single-crystal structure. C60 fullerene was chosen as a representative test material. A 250 nm C60 film was investigated by grazing-incidence X-ray diffraction and the data compared with a Bragg–Brentano X-ray diffraction measurement of the corresponding C60 powder. The diffraction patterns of both powder and film were used to calculate the pair distribution function (PDF), which allowed an investigation of the short-range order of the structures. With the help of the PDF, a structure model for the C60 molecular arrangement was determined for both C60 powder and thin film. The results agree very well with a classical whole-pattern fitting approach for the C60 diffraction patterns.

Evidence of x-ray absorption-edge shift as a function of luminescence wavelength in porous silicon

2000 ◽  
Vol 62 (15) ◽  
pp. 9911-9914 ◽  
Author(s):  
G. Dalba ◽  
N. Daldosso ◽  
P. Fornasini ◽  
M. Grimaldi ◽  
R. Grisenti ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Absorption Edge ◽  
X Ray ◽  
Absorption Edge Shift ◽  
X Ray Absorption
Sign in / Sign up

Export Citation Format

Share Document