Effect of Preparation Conditions on the Silicon L-Edge In Electrochemically Prepared Porous Silicon

1993 ◽  
Vol 298 ◽  
Author(s):  
T. Van Buuren ◽  
T. Tiedje ◽  
W. Weydanz
Keyword(s):  
Electronic Structure ◽  
High Resolution ◽  
Porous Silicon ◽  
Quantum Confinement ◽  
Light Exposure ◽  
Blue Shift ◽  
Bulk Silicon ◽  
Preparation Conditions ◽  
P Type ◽  
Confinement Model

AbstractHigh resolution measurements of the silicon L-edge absorption in electrochemically prepared porous silicon show that the absorption threshold is shifted to higher energy relative to bulk silicon, and that the shift is dependent on how the porous silicon is prepared. When the porous silicon is made from n-type material with light exposure, the blue shift increases logarithmically with the anodizing current. Porous silicon prepared by anodizing p-type silicon exhibits a blue shift in the L-edge which increases with the time spent in the HF solution after the anodizing potential is turned off. The data are consistent with the quantum confinement model for the electronic structure of porous silicon.

Relationships Between Photoluminescence Spectra and Porosity of Porous Silicon

1994 ◽  
Vol 332 ◽  
Author(s):  
H.Z. Song ◽  
L.Z. Zhang ◽  
B.R. Zhang ◽  
G.G. Qin
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Light Emission ◽  
Photoluminescence Spectra ◽  
Lower Side ◽  
Si Substrates ◽  
Peak Energy ◽  
P Type ◽  
Confinement Model

ABSTRACTIt was found that porous silicon (PS) layers formed on 0.01 Ωcm (111) and 0.02 Ωcm (100) Si substrates show high photoluminescence (PL) peak energies on both lower and higher porosity sides and a minimum of PL peak energy at the moderate porosity, while those formed on 0.8 and 10Ωcm (111) p-type Si substrates show an increase of PL peak energy with porosity on the lower side and a saturation of PL peak energy with porosity on the higher side. These experimental facts are not consistent with the quantum confinement model for light emission of PS, which predicts a monotonous increase of PL peak energy with PS porosity.

Comparison of Porous Silicon Etched Gently and Under Illumination

1994 ◽  
Vol 358 ◽  
Author(s):  
Adam A. Filios ◽  
Raphael Tsu
Keyword(s):  
Porous Silicon ◽  
Thermal Annealing ◽  
Raman Line ◽  
Quantum Confinement ◽  
Blue Shift ◽  
The Other ◽  
Bulk Silicon ◽  
Dominant Mechanism ◽  
Peak Energy ◽  
Photoluminescence Peak

ABSTRACTPorous silicon samples prepared in the dark under "gentle" etching conditions clearly demonstrate effects of quantum confinement, such as a correlation of the photoluminescence peak energy with the downshift of the Raman line from 521 cm−1 for bulk silicon, and a blue shift in the remaining weak photoluminescence after thermal annealing. On the other hand, samples prepared under illumination as well as those heavily etched in the dark, though luminesce brightly, show no significant effects of quantum confinement, suggesting a different dominant mechanism for the observed luminescence.

Gold nanoclusters reductively deposited on porous silicon: morphology and electronic structures

1998 ◽  
Vol 76 (11) ◽  
pp. 1707-1716 ◽  
Author(s):  
I Coulthard ◽  
S Degen ◽  
Y -J Zhu ◽  
T K Sham
Keyword(s):  
Gold Nanoparticles ◽  
Porous Silicon ◽  
Photoelectron Spectroscopy ◽  
Gold Nanoclusters ◽  
Gold Complex ◽  
X Ray Diffraction ◽  
Complex Ions ◽  
X Ray ◽  
Preparation Conditions ◽  
P Type

Utilizing porous silicon as a reducing agent and a substrate, gold complex ions [AuCl4]- were reduced from aqueous solution to produce nanoparticles of gold upon the surface of porous silicon. Scanning electron microscopy (SEM) was utilized to study the morphology of the porous silicon layers and the deposits of gold nanoparticles. It is found that preparation conditions have a profound effect on the morphology of the deposits, especially on porous silicon prepared from a p-type wafer. The gold nanoparticles, varying from micrometric aggregates of clusters of the order of 10 nm, to a distribution of nearly spherical clusters of the order of 10 nm, to strings of ~10 nm were observed and compared to bulk gold metal using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS). These techniques confirm and complement the SEM findings. The potential for this reductive deposition technique is noted.Key words: gold nanostructures, reductive deposition, porous silicon, morphology, X-ray spectroscopy.

ESR Study of Porous Silicon

1992 ◽  
Vol 283 ◽  
Author(s):  
W. Y. Cheung ◽  
S. P. Wong ◽  
I. H. Wilson ◽  
C. F. Kan ◽  
S. K. Hark
Keyword(s):  
Porous Silicon ◽  
Spin Density ◽  
Light Emission ◽  
Blue Shift ◽  
Esr Spectra ◽  
Peak Position ◽  
Silicon Substrates ◽  
Post Annealing ◽  
G Value ◽  
P Type

ABSTRACTA detailed ESR study has been performed on porous silicon on both <100> and <111> p-type silicon substrates prepared using anodization in HF under a range of conditions and the results are correlated with the light emission properties. It is found that the ESR spectra are dependent upon the orientation of the samples. The ESR defect centers are identified to be the Pb centers or Pbo centers of the Si-SiO2 system from the g-value anisotropy maps. The variation of the spin density Ns with annealing conditions has also been studied for samples annealed either in nitrogen or oxygen ambient at 200°C for various time intervals. It is concluded that the increase or decrease of Ns are due to the generation or elimination of the Pb or Pbo centers in conjunction with the oxidation process during annealing. From PL study of these samples, it is found that there is no simple correlation between the spin density and the PL intensity. However, a blue shift in the PL peak position was observed both in samples after a post-annealing etch in HF solution, and in samples annealed in oxygen without a post-annealing etch. This blue shift supports the quantum confinement model of light emission from porous silicon.

Photoluminescence in Porous Silicon: Evidence for the Quantum Confinement Model

1991 ◽  
Vol 256 ◽  
Author(s):  
David L. Naylor ◽  
Sung B. Lee ◽  
John C. Pincenti ◽  
Brett E. Bouma
Keyword(s):  
Porous Silicon ◽  
Hydrofluoric Acid ◽  
Quantum Wire ◽  
Quantum Confinement ◽  
Electrochemical Etching ◽  
Photoluminescence Spectra ◽  
Peak Wavelength ◽  
Effects Of Temperature ◽  
Good Agreement ◽  
Confinement Model

ABSTRACTPhotoluminescence spectra have been measured in porous silicon following electrochemical etching in dilute hydrofluoric acid (HF). The effects of HF concentration during etching on the efficiency and peak wavelength of photoluminescence have been investigated. The effects of temperature between 25°C and 200°C on PL spectra have been recorded. Photoluminescence lifetimes as a function of wavelength have been studied following ultrashort UV photoexcitation. A number of lifetime components in the decay are observed the longest in good agreement over the wavelength range of 500 to 600 nm with a silicon quantum wire model. At longer wavelengths a departure from lifetimes of the wire model is observed and two hypotheses for the discrepancy are presented.

Effects of Indium Depositions on Porous Silicon Nanostructure (PSN)

2006 ◽  
Vol 517 ◽  
pp. 267-271
Author(s):  
Shahrum Abdullah ◽  
Muhamad Rasat Muhamad ◽  
K.A. Sekak
Keyword(s):  
Porous Silicon ◽  
Integrated Circuits ◽  
Blue Shift ◽  
Cathodic Electrodeposition ◽  
Light Emitter ◽  
Indium Doping ◽  
Silicon Nanostructure ◽  
P Type ◽  
Porous Silicon Nanostructure ◽  
Contact Electrode

The effects of Indium doped on Porous Silicon Nanostructure (PSN) have been studied. The Electroluminescence studies on Indium-doped porous silicon nanostructure (In:PSN) are presented. The main objective of this paper is study the EL effects of Indium doping on PSN. Porous silicon nanostructure layers have been formed by anodically etching unpolished p-type Si [100] wafer with surface resistivity of 1-10 ohm cm-1 in Hydroflouric (HF) solution at 1:1 ratio of Ethanol. Indium (In) was doped on PSN using cathodic electrodeposition composed of InCl3 and ethanol electrolythe. A diode structure has been fabricated comprising semi-transparent Au/In:PSN/p-Si substrate/Al ohmic contact electrode to observe the EL spectra. The In:PSN device shows increasing on EL and PL Intensity as well as blue-shift EL and PL spectrum is observed. Possible reasons for the enhancement will be discussed. Technological application of PSN as a light emitter would have significant impact on numerous technologies such as display panels or integrated circuits with optoelectronic devices (IO) on board and sensors.

Raman and Optical Characterization of Porous Silicon

1991 ◽  
Vol 256 ◽  
Author(s):  
J. F. Harvey ◽  
H. Shen ◽  
R. A. Lux ◽  
M. Dutita ◽  
J. Pamulapati ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Room Temperature ◽  
Thermal Dissociation ◽  
Life Time ◽  
High Energy ◽  
Bulk Silicon ◽  
Energy Peak ◽  
Time Changes

ABSTRACTRaman spectra from electrochemically etched porous silicon are correlated with photoluminescence (PL) data from the same spots of the sample. This correlation is consistent with optical properties of quantum confinement. The dielectric constant determined from angle resolved ellipsometry gives values far below that of bulk silicon. This reduction is due to the combined effects of voids as well as quantum confinement. The PL spectrum shows a weak high energy peak around 2.8eV in addition to the strong broad peak at 1.5 to 1.9eV. The temperature dependence of PL resembles that of bound excitons such as Si:S, having a thermal dissociation energy of 100 meV near room temperature. The radiation life time changes from tens of microseconds near room temperature to a few milliseconds at liquid helium temperatures. The rapid increase in lifetime and decrease in PL intensity at low temperatures indicates that phonons are probably involved.

Can Oxidation and Other Treatments Help Us Understand the Nature of Light-Emitting Porous Silicon?

1993 ◽  
Vol 298 ◽  
Author(s):  
P.M. Fauchet ◽  
E. Ettedgui ◽  
A. Raisanen ◽  
L.J. Brillson ◽  
F. Seiferth ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Room Temperature ◽  
Vacuum Annealing ◽  
Surface States ◽  
Careful Analysis ◽  
Experimental Results ◽  
Dangling Bonds ◽  
Light Emitting ◽  
Confinement Model

AbstractUsing a careful analysis of the properties of light-emitting porous silicon (LEpSi), we conclude that a version of the “smart” quantum confinement model which was first proposed by F. Koch et al [Mat. Res. Soc. Symp. Proc. 283, 197 (1993)] and allows for the existence of surface states and dangling bonds, is compatible with experimental results. Among the new results we present in support of this model, the most striking ones concern the strong infrared photoluminescence that dominates the room temperature cw spectrum after vacuum annealing above 600 K.

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