scholarly journals RETRACTED ARTICLE: Enhancement of the blue photoluminescence intensity for the porous silicon with HfO2 filling into microcavities

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Ran Jiang ◽  
Xianghao Du ◽  
Weideng Sun ◽  
Zuyin Han ◽  
Zhengran Wu
Keyword(s):  
Porous Silicon ◽  
Photoluminescence Intensity ◽  
Retracted Article ◽  
Blue Photoluminescence

Synthesis, Photoluminescence and Bio-Targeting Applications of Blue Graphene Quantum Dots

2016 ◽  
Vol 16 (4) ◽  
pp. 3457-3467 ◽  
Author(s):  
Jigang Wang ◽  
Ji Zhou ◽  
Wenhua Zhou ◽  
Jilong Shi ◽  
Lun Ma ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Graphene Oxide ◽  
Sodium Hydroxide ◽  
Heating Temperature ◽  
Thin Sheet ◽  
Graphene Quantum Dots ◽  
Photoluminescence Intensity ◽  
Cytotoxic Effects ◽  
Different Temperatures ◽  
Blue Photoluminescence

Chemical derived graphene oxide, an atomically thin sheet of graphite with two-dimensional construction, offers interesting physical, electronic, thermal, chemical, and mechanical properties that are currently being explored for advanced physics electronics, membranes, and composites. Herein, we study graphene quantum dots (GQD) with the blue photoluminescence under various parameters. The GQD samples were prepared at different temperatures, and the blue photoluminescence intensity of the solution improved radically as the heating temperatures increased. Concerning PL peak and intensity of the quantum dots, the results demonstrated dependence on time under heating, temperature of heating, and pH adjusted by the addition of sodium hydroxide. After hydrothermal synthesis routes, the functional groups of graphene oxide were altered the morphology showed the stacking configuration, and self-assembled structure of the graphene sheets with obvious wrinkles appeared at the edge structures. In addition, absorption, PL, and PLE spectra of the graphene quantum dots increase with different quantities of sodium hydroxide added. Finally, using GQD to target PNTIA cells was carried out successfully. High uptake efficiency and no cytotoxic effects indicate graphene quantum dots can be suitable for bio-targeting.

scholarly journals Porous Silicon Structural Evolution from In-Situ Luminescence and Raman Measurements

1996 ◽  
Vol 431 ◽  
Author(s):  
D. R. Tallant ◽  
M. J. Kelly ◽  
T. R. Guilinger ◽  
R. L. Simpson
Keyword(s):  
Porous Silicon ◽  
Silicon Surface ◽  
Structural Evolution ◽  
Surface Oxidation ◽  
Ethanol Solution ◽  
Nonradiative Recombination ◽  
Photoluminescence Intensity ◽  
Exciton Migration ◽  
Photoluminescence Mechanism

AbstractWe performed in-situ photoluminescence and Raman measurements on an anodized silicon surface in the HF/ethanol solution used for anodization. The porous silicon thereby produced, while resident in HF/ethanol, does not immediately exhibit intense photoluminescence. Intense photoluminescence develops spontaneously in HF/ethanol after 18–24 hours or with replacement of the HF/ethanol with water. These results support a quantum confinement mechanism in which exciton migration to traps and nonradiative recombination dominates the de-excitation pathways until silicon nanocrystals are physically separated and energetically decoupled by hydrofluoric acid etching or surface oxidation. The porous silicon surface, as produced by anodization, shows large differences in photoluminescence intensity and peak wavelength over millimeter distances. Parallel Raman measurements implicate nanometer-size silicon particles in the photoluminescence mechanism.

scholarly journals The blue photoluminescence from rare earths-doped porous silicon

2004 ◽  
Vol 53 (5) ◽  
pp. 1562
Author(s):  
Peng Ai-Hua ◽  
Xie Er-Qing ◽  
Jia Chang-Wen ◽  
Jiang Ran ◽  
Lin Hong-Feng ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Rare Earths ◽  
Blue Photoluminescence

Depositing Metals into Porous Silicon - the Impact on Luminescence

1994 ◽  
Vol 358 ◽  
Author(s):  
P. Steiner ◽  
F. Kozlowski ◽  
W. Lang
Keyword(s):  
Porous Silicon ◽  
Porous Layer ◽  
Electron Microprobe ◽  
Uv Light ◽  
Electrochemical Process ◽  
Photoluminescence Intensity ◽  
Spectral Position ◽  
Metal Atoms ◽  
Metal Treatment ◽  
The Impact

ABSTRACTIndium, tin, antimony and aluminum are deposited by an electrochemical process into the pores of n-type porous silicon which is anodized with ultraviolet light applied during formation. The presence of these metal atoms in the porous layer is checked by electron microprobe measurement. As reported previously, UV-light etched material shows red photoluminescence (630 nm) and blue electroluminescence (470 nm) without the metal treatment. After metal deposition the photoluminescence intensity decreases slightly (factor 0.5 - 0.8), whereas the spectral position remains constant. The electroluminescence efficiency is significantly enhanced by indium, aluminum and tin in the pores (factor 5 - 90). The tin and antimony treatment causes a red shift to 580 nm and 740 nm, respectively. The conductivity is slightly increased by all kinds of metals by a factor 2-5.

Instrumentation for Reliably Determining Porous Silicon Photoluminescence Responses to Gaseous Analyte Vapors

2016 ◽  
Vol 70 (12) ◽  
pp. 1974-1980 ◽  
Author(s):  
Justin M. Reynard ◽  
Nathan S. Van Gorder ◽  
Caley A. Richardson ◽  
Richie D. Eriacho ◽  
Frank V. Bright
Keyword(s):  
Porous Silicon ◽  
Vapor Concentration ◽  
Photoluminescence Intensity ◽  
Spectral Measurements ◽  
Temperature Dependent ◽  
Time Resolved ◽  
Hyper Spectral ◽  
New Instrumentation ◽  
Time Resolved Photoluminescence ◽  
New System

We report new instrumentation for rapidly and reliably measuring the temperature-dependent photoluminescence response from porous silicon as a function of analyte vapor concentration. The new system maintains the porous silicon under inert conditions and it allows on-the-fly steady-state and time-resolved photoluminescence intensity and hyper-spectral measurements between 293 K and 450 K. The new system yields reliable data at least 100-fold faster in comparison to previous instrument platforms.

Localisation of Carriers in Porous Silicon

1996 ◽  
Vol 452 ◽  
Author(s):  
I. Mihalcescu ◽  
J. C. Vial ◽  
R. Romestain
Keyword(s):  
Simple Model ◽  
Porous Silicon ◽  
Temperature Variation ◽  
Time Evolution ◽  
Decay Time ◽  
Additional Assumption ◽  
Shape Evolution ◽  
Photoluminescence Intensity ◽  
Photoluminescence Decay ◽  
Strong Localization

AbstractWe analyze the intensity and decay time evolution of the porous silicon luminescence upon anodic oxidation, aging, chemiral thinning and temperature variation. Strong analogies are pointed out for the photoluminescence intensity as well as for the photoluminescence decay shape evolution. They are interpreted by the variation of the extension of the carrier wavefunction induced by the modification of potential barrier efficiencies. No additional assumption such as hopping of carriers was necessary to explain the decay shapes well fitted by stretched exponential. On the contrary our observations and our simple model are in favor of a strong localization of carriers. Some experimental results are revisited within the frame of this model.

Multiparametric sensor for air pollutants based on a porous silicon optical microcavity

2000 ◽  
Vol 638 ◽  
Author(s):  
Z. Gaburro ◽  
G. Faglia ◽  
C. Baratto ◽  
G. Sberveglieri ◽  
L. Pavesi
Keyword(s):  
Porous Silicon ◽  
Electrical Conduction ◽  
Volume Ratio ◽  
Peak Shift ◽  
Peak Position ◽  
Index Of Refraction ◽  
Photoluminescence Intensity ◽  
Spectral Position ◽  
Additional Information ◽  
Optical Microcavities

AbstractWe experimentally demonstrate that porous silicon optical microcavities can be effectively used as multi-parametric gas sensors. As known, the photoluminescence intensity and electrical conduction of porous silicon are strongly dependent on environmental properties, such as the dipole moment of molecules of surrounding gases. The sensitivity is large due to the large surface/volume ratio of porous silicon. While these effects can be observed in any porous silicon structure, microcavities of porous silicon allow an additional sensing parameter, i.e. the spectral position of the resonance cavity peak. The position of the peak depends on the index of refraction of the environment, and gives independent additional information. Moreover, we show that the dynamic response of the peak shift is much faster comparing the other sensing parameters. The combined effects on the peak position, luminescence intensity and electrical conduction can allow discrimination between different substances, and therefore porous silicon optical microcavities can work as multi-parametric optical/electrical sensors. We report detection of 1 ppm of NO2 and 500 ppm of ethanol at room temperature. With NO2, the electrical conduction increases and PL quenches, but the peak does not shift, whereas the peak shifts with ethanol (no significant PL quenching is observed at 500 ppm). This suggests that discrimination between different species can be achieved.

Porous Silicon Photoluminescence Versus HF Etching: No Correlation with Surface Hydrogen Species

1992 ◽  
Vol 283 ◽  
Author(s):  
M. B. Robinson ◽  
A. C. Dillon ◽  
S. M. George
Keyword(s):  
Porous Silicon ◽  
Ftir Spectroscopy ◽  
Hydrofluoric Acid ◽  
Etching Time ◽  
Photoluminescence Intensity ◽  
Surface Species ◽  
Initial Sample ◽  
Surface Hydrogen

ABSTRACTThe photoluminescence and infrared absorbance of electrochemically anodized porous silicon samples were examined as a function of hydrofluoric acid (HF) etching time. Transmission FTIR spectroscopy measurements revealed that the infrared absorbance from silicon hydrogen surface species was largest for the initial porous silicon samples and immediately decreased with HF etching. In contrast, the photoluminescence did not appear until after HF etching times of 20–80 minutes, depending on initial sample porosity. Subsequently, the photoluminescence intensity increased, reached a maximum, and then progressively decreased versus HF etching time. These HF etching results demonstrate that there is no direct correlation between the photoluminescence and the silicon hydrogen surface species.

The Effect of Starting Silicon Crystal Structure on Photoluminescence Intensity of Porous Silicon

1994 ◽  
Vol 358 ◽  
Author(s):  
W. B. Dubbelday ◽  
S. D. Russell ◽  
K. L. Kavanagh
Keyword(s):  
Porous Silicon ◽  
Single Crystal ◽  
Amorphous Silicon ◽  
Silicon Crystal ◽  
Single Crystal Silicon ◽  
Luminescent Materials ◽  
Photoluminescence Intensity ◽  
Crystal Silicon ◽  
Chemical Etch ◽  
Porosity Measurements

ABSTRACTIn previous work we reported that porous silicon (PS) films formed using a dilute HF:HNO3 chemical etch on polycrystalline, implant damaged single crystal, or amorphous starting material have luminescent characteristics that differ from PS fabricated on single crystal silicon1. Polycrystalline and implant damaged porous silicon exhibits brighter luminescence compared to single crystal silicon etched under identical conditions. No photoluminescence is detected from the porous amorphous silicon. In this work these effects are examined using HF:NaNO2 solutions with freely available NO2. The accelerated etching effects from work damage are reduced, and the PS from polycrystalline and implant damaged silicon luminesce with the same intensity as the PS from single crystal silicon. Again, etched amorphous silicon does not luminesce. TEM and EDX porosity measurements are used to determine the differences in structure and etching characteristics between the luminescent and non-luminescent materials.

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