Intense RT Visible Photoluminescence from Anodized Amorphous and Nanocrystalline Silicon Films

1992 ◽  
Vol 283 ◽  
Author(s):  
E. Bustarret ◽  
J. C. Bruyere ◽  
F. Muller ◽  
M. Ligeon
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Nanocrystalline Silicon ◽  
Current Debate ◽  
X Ray ◽  
Boron Doped ◽  
Intense Luminescence ◽  
Conductive Substrates ◽  
Uv Excitation ◽  
Room Temperature Luminescence

ABSTRACTHeavily Boron-doped micrometer-thick amorphous (a-Si:B:H) or nanocrystalline (nc-Si) silicon layers have been deposited on a variety of conductive substrates by the 50 KHz PECVD of SiH4 / B2H6 / H2 mixtures at 320°C. These films have been partially electro-oxidized in a HF solution and then anodically oxidized in water in a manner similar to that yielding luminescent porous monocrystalline silicon layers (PcSL). Although the anodized films are x-ray amorphous, they yield intense luminescence properties at room temperature very similar to those of anodically oxidized PcSL with a similar vibrational spectrum. In both anodically oxidized materials, aging is shown to improve the external quantum efficiency. In amorphous anodized layers, optical microscopy under UV excitation showed strongly luminescent strain-related heterogeneities (20 μ,m in diameter) connected by non luminescent channels. The incidence of our results on the current debate about the origin of visible room-temperature luminescence in porous silicon and Si:O:H systems is discussed.

Deposition of Photoluminescent Nanocrystalline Silicon Films by SiF4-SiH4-H2 Plasmas

1996 ◽  
Vol 452 ◽  
Author(s):  
G. Cicala ◽  
G. Bruno ◽  
P. Capezzuto ◽  
L. Schiavulli ◽  
V. Capozzi ◽  
...  
Keyword(s):  
Grain Size ◽  
Porous Silicon ◽  
Vapor Deposition ◽  
Room Temperature ◽  
Energy Gap ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Average Grain Size

AbstractVisible photoluminescence at 1.62 eV has been observed at room temperature from fluorinated and hydrogenated nanocrystalline silicon (nc-Si:H,F) produced in a typical plasma enhanced chemical vapor deposition system. The use of SiF4-SiH4-H2 mixture, because of the H2 dilution and the presence of SiF4, favours the amorphous - crystalline transition through the etching process of the amorphous phase. The x - ray diffraction measurements give an average grain size of about 100 Å. The presence of these nanocrystals shifts the absorption edge of the films towards higher energy. An energy gap of 2.12 eV is estimated, although the hydrogen content in the material is only 4.5 at. %. The temperature dependence of the photoluminescence behaves similarly to that of porous silicon.

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.

VUV- and Soft X-Ray-Induced Optical Luminescence and X-Ray Absorption Fine Structures of Porous Silicon

1992 ◽  
Vol 281 ◽  
Author(s):  
T. K. Sham ◽  
D. T. Jiang ◽  
I. Coulthard ◽  
J. W. Lorimer ◽  
X. H. Feng ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Total Electron Yield ◽  
Total Electron ◽  
X Ray ◽  
Absorption Fine ◽  
Electron Yield ◽  
Optical Luminescence ◽  
Fine Structures ◽  
X Ray Absorption ◽  
Uv Excitation

ABSTRACTOptical luminescence in porous silicon induced by soft X-ray and vacuum UV excitation with energies in the vicinity of the Si K-edge (1838 eV) and the Si L-edge (99 eV) has been observed. The luminescence has been used, together with total electron yield, to record X-ray absorption fine structure (XAFS) in the near-edge region of both Si edges. The near- edge spectra recorded simultaneously with either luminescence or total electron yield were compared, and the implications of these measurements for the structure of porous silicon are discussed.

Effect of Au on the Performance of Porous Silicon/V2O5 Nanorods Heterojunctions to NO2 Gas

NANO ◽  
2016 ◽  
Vol 11 (07) ◽  
pp. 1650079 ◽  
Author(s):  
Wenjun Yan ◽  
Ming Hu ◽  
Jiran Liang ◽  
Dengfeng Wang ◽  
Yulong Wei ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Porous Silicon ◽  
Room Temperature ◽  
Au Nanoparticles ◽  
Analytical Techniques ◽  
Heating Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

A novel composite of Au-functionalized porous silicon (PS)/V2O5 nanorods (PS/V2O5:Au) was prepared to detect NO2 gas. PS/V2O5 nanorods were synthesized by a heating process of pure vanadium film on PS, and then the obtained PS/V2O5 nanorods were functionalized with dispersed Au nanoparticles. Various analytical techniques, such as field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), have been employed to investigate the properties of PS/V2O5:Au. Herein, the PS/V2O5:Au sample exhibited improved NO2-sensing performances in response, stability and selectivity at room temperature (25[Formula: see text]C), compared with the pure PS/V2O5 nanorods. These phenomena were closely related to not only the dispersed Au nanoparticles acting as a catalyst but also the p-n heterojunctions between PS and V2O5 nanorods. Whereas, more Au nanoparticles suppressed the improvement of response to NO2 gas.

Synthesis of Nanophase Noble Metal Systems Utilizing Porous Silicon

1996 ◽  
Vol 457 ◽  
Author(s):  
I. Coulthard ◽  
T. K. Sham
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Porous Silicon ◽  
Noble Metal ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Visible Range ◽  
X Ray ◽  
Metallic Salt ◽  
Scanning Electron

ABSTRACTApart from its well known ability to luminesce very intensely at room temperature in the visible range, porous silicon is also an effective reducing agent. We report the formation of several noble metal (Pd, Ag, Au, Pt) nanostructures by reductive dispersion of metal ions from aqueous solutions onto the surface of porous silicon. The nanophase systems produced by reductive deposition vary with the element deposited and the metallic salt utilized in the process. The resulting nanophase systems were studied using a variety of techniques including: scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and spectroscopie methods using synchrotron radiation.

Comparison of room temperature photoluminescence decays in anodically oxidized crystalline and X-ray-amorphous porous silicon

1993 ◽  
Vol 57 (1-6) ◽  
pp. 105-109 ◽  
Author(s):  
E. Bustarret ◽  
I. Mihalcescu ◽  
M. Ligeon ◽  
R. Romestain ◽  
J.C. Vial ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
X Ray ◽  
Room Temperature Photoluminescence

Synthesis, Crystal Structure, Luminescence, and Nonlinear Optical Properties of 2-[(E)-[[4-[2-(4-Methoxyphenyl)ethynyl]phenyl] imino]methyl]-4- [(E)-phenyldiazenyl]phenol

2020 ◽  
Vol 17 (8) ◽  
pp. 618-623
Author(s):  
Sagar Subhash Mohite ◽  
Aditya Babasaheb Patil-Deshmukh ◽  
Sanjay Shamrao Chavan
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Nonlinear Optical ◽  
Room Temperature ◽  
Second Harmonic ◽  
Monoclinic Structure ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Shg Efficiency ◽  
Room Temperature Luminescence

2-((E)-((4-((4-methoxyphenyl)ethynyl)phenyl)imino)methyl-4-((E)phenyldiazenyl)phenol (1) have been synthesized and characterized. X-ray single crystal diffraction study of the compound 1 reveal a monoclinic structure. Room temperature luminescence is observed for 1 in CH2Cl2 solution due to π* → π transition. The SHG efficiency by Kurtz powder technique indicating the compound 1 displayed the second harmonic generation (SHG) property.

Comparative Studies of Optical Spectra in PbF2 at Different Excitations

1994 ◽  
Vol 348 ◽  
Author(s):  
V. K. Egorov ◽  
N.V. Klassen ◽  
V.D. Negrii ◽  
V.M. Prokopenko ◽  
S.Z. Shmurak ◽  
...  
Keyword(s):  
Comparative Studies ◽  
Room Temperature ◽  
Spectral Characteristics ◽  
Optical Spectra ◽  
Lead Fluoride ◽  
X Ray ◽  
Luminescence Centers ◽  
Room Temperature Luminescence ◽  
Α Particles

ABSTRACTThe spectral characteristics for cubic and orthorhombic lead fluoride excited by light with energies of 5–2.5 eV, X-ray, and α-particles were studied. It is shown that the room temperature luminescence in orthorhombic lead fluoride is connected with resonance excitations of some luminescence centers. Possible models of the centers responsible for this phenomenon are proposed.

Functionalization of Porous Silicon Surfaces by Solution-Phase Reactions with Alcohols and Grignard Reagents

1998 ◽  
Vol 536 ◽  
Author(s):  
N. Y. Kim ◽  
P. E. Laibinis
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Organic Molecules ◽  
Solution Phase ◽  
Silicon Surfaces ◽  
Covalent Attachment ◽  
Grignard Reagents ◽  
X Ray ◽  
Reaction Proceeds ◽  
Support Evidence

AbstractThis paper describes the covalent attachment of various organic molecules to the hydrogenterminated surface of porous silicon using alcohols and Grignard reagents. With alcohols, the chemical reaction forms Si-O-C attachments to the silicon substrate and requires modest heating (40–70 °C). With Grignard reagents, the reaction proceeds at room temperature and forms a covalent film that is attached by Si-C bonds to the silicon support. Evidence for these reactions is provided by infrared and x-ray photoelectron spectroscopies.

Activation of Lead Fluoride Room Temperature Luminescence by Structural Modifications

1994 ◽  
Vol 348 ◽  
Author(s):  
D.L. Alov ◽  
A.V. Bazhenov ◽  
V.K. Egorov ◽  
G.A. Emelchenko ◽  
N.V. Klassen ◽  
...  
Keyword(s):  
Room Temperature ◽  
Structural Characteristics ◽  
Structural Defects ◽  
Luminescence Spectra ◽  
Lead Fluoride ◽  
Light Emitting ◽  
X Ray ◽  
Structural Modifications ◽  
Excited Luminescence ◽  
Room Temperature Luminescence

ABSTRACTThe connection of lead fluoride luminescence properties with its structural characteristics has been studied. Single crystals of the cubic and orthorombic phases, cubic and orthorombic powders, pressure compacted orthorombic ceramics, plastically deformed crystals were used. The photo- and X-ray excited luminescence spectra have been investigated. The experimental results have shown that the room temperature luminescence of lead fluoride can be accounted for local light emitting centers which are produced by the intrinsic structural defects in the orthorombic lead fluoride.

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