Light Controlled Photoluminescence Relaxation in Porous Silicon

1994 ◽  
Vol 358 ◽  
Author(s):  
R. Czaputa ◽  
R. Fritzl ◽  
A. Popitsch
Keyword(s):  
Porous Silicon ◽  
Chemical Structure ◽  
Room Temperature ◽  
Relaxation Effect ◽  
Ambient Atmosphere ◽  
Surface Chemical ◽  
Dangling Bond ◽  
Nanoporous Silicon ◽  
Pl Intensity ◽  
Modification Of The Surface

ABSTRACTWe report results of photoluminescence (PL), FTIR and ESR investigations on nanoporous silicon (PS) where a reversible PL intensity relaxation effect in the chemically oxidised material is observed. To be activated the effect needs, however, additional preparation steps including light irradiation and ageing in ambient atmosphere. After illumination with visible light, the PL intensity is remarkably diminished. However it recovers in the dark within the time scale of minutes to hours under ambient atmosphere at room temperature. This cycle can be repeated several times. We show that the variation of the PL intensity is anticorrelated to an ESR signal attributed to silicon dangling bonds. From the IR spectrum, however, no significant change of the pore surface chemical structure can be observed during a cycle. Therefore we conclude that the variation of the PL intensity is rather controlled by a metastable change in the number of dangling bond centers than by modification of the surface chemistry in the porous silicon system.

Influence of AgNO3 on Photoluminescence Properties of Porous Silicon

2012 ◽  
Vol 486 ◽  
pp. 239-242 ◽  
Author(s):  
Hong Yan Zhang ◽  
Xiao Yi Lv ◽  
Zhen Hong Jia
Keyword(s):  
Silver Nanoparticles ◽  
Porous Silicon ◽  
Specific Surface ◽  
Room Temperature ◽  
Photoluminescence Properties ◽  
Pl Intensity ◽  
Made In

Porous silicon (PS) has the strong photoluminescence (PL) at room temperature and high specific surface. In this paper, we have fabricated the PS coated with silver nanoparticles as a substrate. The result shows that the substrate made in this way is stable for more than twenty days and the strong PL intensity of PS is around 584nm after immersed into solution of AgNO3. The formation of SiAg bond was demonstrated to be responsible for the improvement of PL properties.

Surface-Related Photoluminescence Effects in GaN

2002 ◽  
Vol 743 ◽  
Author(s):  
M. A. Reshchikov ◽  
M. Zafar Iqbal ◽  
D. Huang ◽  
L. He ◽  
H. Morkoç
Keyword(s):  
Molecular Beam Epitaxy ◽  
Luminescence Band ◽  
Room Temperature ◽  
Molecular Beam ◽  
Uv Exposure ◽  
Ambient Atmosphere ◽  
Yellow Luminescence ◽  
Uv Illumination ◽  
Pl Intensity ◽  
Small Change

ABSTRACTPhotoluminescence (PL) from GaN epilayers is found to be sensitive to the ambient atmosphere and length of UV exposure. We studied the effect of UV illumination in different ambients including air, oxygen, nitrogen and hydrogen gases on room-temperature PL of GaN grown on sapphire by molecular beam epitaxy. In some samples the PL intensity increased markedly in vacuum as compared to excitation in air, whereas in others it decreased appreciably. While air and oxygen showed strong reversible variation of the PL intensity as compared to vacuum, nitrogen and hydrogen atmospheres led to a very small change. In some samples we observed a shift of the yellow luminescence band with change of ambient, in others no shift was detected. PL intensity also changed during UV irradiation when the sample was in air ambient. Possible reasons for our observations are discussed.

Reversible and Irreversible Light-Induced Change of Photoluminescence in Porous Silicon

1995 ◽  
Vol 378 ◽  
Author(s):  
Suk-Ho Choi ◽  
Byoung-Hun Mun
Keyword(s):  
Fourier Transform ◽  
Porous Silicon ◽  
Room Temperature ◽  
Irreversible Process ◽  
Laser Light ◽  
Light Exposure ◽  
Peak Position ◽  
Continuous Laser ◽  
Ftir Studies ◽  
Pl Intensity

AbstractWe have investigated the light-induced change of photoluminescence(PL) and its recovery in porous silicon. The exposure of the porous silicon to continuous laser light in vacuum results in the quenching of the PL intensity, which is almost fully recovered by simply keeping the samples in vacuum or in air at room temperature for a few days. When the light exposure is done in air, the PL spectra of the samples with initial PL peak at 800 nm are blue-shifted to the peak position at 740 nm and the samples with the initial PL spectrum peaked at 740 nm shows only a rise of PL intensity without any change of its peak position. Fourier transform infrared(FTIR) studies suggest that the light-induced change of PL in air is a irreversible process and occurs as a result of optically induced replacement of some of the Si-H bonds with O-Si-H bonds or adsorption of oxygen with hydrogen loss.

Degradation in a Methyl-phenyl Co-Polymeric Polysilane for LED Applications

2003 ◽  
Vol 769 ◽  
Author(s):  
Asha Sharma ◽  
Deepak ◽  
Monica Katiyar ◽  
Satyendra Kumar ◽  
V. Chandrasekhar ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Light Source ◽  
Room Temperature ◽  
Light Exposure ◽  
Room Temperature Photoluminescence ◽  
Pl Spectrum ◽  
Pl Intensity ◽  
Methyl Phenyl

AbstractThe optical degradation of polysilane copolymer has been studied in spin cast thin films and solutions using light source of 325 nm wavelength. The room temperature photoluminescence (PL) spectrum of these films show a sharp emission at 368 nm when excited with a source of 325 nm. However, the PL intensity deteriorates with time upon light exposure. Further the causes of this degradation have been examined by characterizing the material for its transmission behaviour and changes occurring in molecular weight as analysed by GPC data.

scholarly journals Structural and Enhanced Optical Properties of Stabilized γ‒Bi2O3 Nanoparticles: Effect of Oxygen Ion Vacancies

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1023 ◽  
Author(s):  
Ashish Chhaganlal Gandhi ◽  
Chia-Liang Cheng ◽  
Sheng Yun Wu
Keyword(s):  
Room Temperature ◽  
Excess Oxygen ◽  
Ambient Atmosphere ◽  
Photoluminescence Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Band Emission ◽  
Oxygen Ion ◽  
Integrated Intensity ◽  
Effect Of Oxygen

We report the synthesis of room temperature (RT) stabilized γ–Bi2O3 nanoparticles (NPs) at the expense of metallic Bi NPs through annealing in an ambient atmosphere. RT stability of the metastable γ–Bi2O3 NPs is confirmed using synchrotron radiation powder X-ray diffraction and Raman spectroscopy. γ–Bi2O3 NPs exhibited a strong red-band emission peaking at ~701 nm, covering 81% integrated intensity of photoluminescence spectra. Our findings suggest that the RT stabilization and enhanced red-band emission of γ‒Bi2O3 is mediated by excess oxygen ion vacancies generated at the octahedral O(2) sites during the annealing process.

Temperature Dependent Line-Shape of the Silicon Dangling Bond EPR-Resonance in Polycrystalline Silicon

1996 ◽  
Vol 452 ◽  
Author(s):  
N. H. Nickel ◽  
E. A. Schiff
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Polycrystalline Silicon ◽  
Room Temperature ◽  
Dangling Bond ◽  
Temperature Dependent ◽  
Paramagnetic Resonance ◽  
Temperature Electron ◽  
Motional Narrowing ◽  
G Value ◽  
Electron Paramagnetic

AbstractThe temperature dependence of the silicon dangling-bond resonance in polycrystalline (poly-Si) and amorphous silicon (a-Si:H) was measured. At room temperature, electron paramagnetic resonance (EPR) measurements reveal an isotropie g-value of 2.0055 and a line width of 6.5 and 6.1 G for Si dangling-bonds in a-Si:H and poly-Si, respectively. In both materials spin density and g-value are independent of temperature. While in a-Si:H the width of the resonance did not change with temperature, poly-Si exhibits a remarkable T dependence of ΔHpp. In unpassivated poly-Si a pronounced decrease of ΔHpp is observed for temperatures above 300 K. At 384 K ΔHpp reaches a minimum of 5.1 G, then increases to 6.1 G at 460 K, and eventually decreases to 4.6 G at 530 K. In hydrogenated poly-Si ΔHpp decreases monotonically above 425 K. The decrease of ΔHpp is attributed to electron hopping causing motional narrowing. An average hopping distance of 15 and 17.5 Å was estimated for unhydrogenated and H passivated poly-Si, respectively.

Synthesis and properties of phthalonitrile-based resins containing spirocycle acetal

2020 ◽  
pp. 095400832097759
Author(s):  
Ke Li ◽  
Hua Yin ◽  
Kun Yang ◽  
Pei Dai ◽  
Ling Han ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Chemical Structure ◽  
Room Temperature ◽  
Laser Desorption Ionization ◽  
Scanning Calorimetry ◽  
Rheological Analysis ◽  
Ionization Time ◽  
Dynamic Mechanical ◽  
Nmr Spectrometry ◽  
Current Context

Designing novel low-melting, high-rigidity phthalonitrile resin is of great significance in the current context of development. In this study, rigid spirocycle acetal structure was introduced into phthalonitrile to reduce the melting point and maintain their thermal stability. The chemical structure of resins was confirmed by nuclear magnetic resonance (NMR) spectrometry, matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry and Fourier-transform infrared (FTIR) spectroscopy. The curing behaviors were studied by differential scanning calorimetry (DSC). Thermal stability and mechanical properties of the cured resins were investigated by dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The processability was studied by rheological analysis. The results indicated the three monomers had a low melting temperature, wide processing windows and low viscosities. These polymers did not exhibit Tg from room temperature to 400°C, exhibited superb dynamic mechanical property and thermal stability.

Room-temperature electroluminescence from erbium-doped porous silicon

1999 ◽  
Vol 75 (25) ◽  
pp. 3989-3991 ◽  
Author(s):  
Herman A. Lopez ◽  
Philippe M. Fauchet
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Erbium Doped

Stabilization of Porous Silicon Free-Standing Coupled Optical Microcavities by Surface Chemical Modification

2019 ◽  
Vol 16 (3) ◽  
pp. 211-219 ◽  
Author(s):  
Bernard Gelloz ◽  
Kouichiro Murata ◽  
Toshiyuki Ohta ◽  
Mher Ghulinyan ◽  
Lorenzo Pavesi ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Chemical Modification ◽  
Surface Chemical ◽  
Free Standing ◽  
Optical Microcavities ◽  
Surface Chemical Modification

scholarly journals Влияние условий роста и уровня легирования на кинетику люминесценции слоев Ge : Sb, выращенных на кремнии

2020 ◽  
Vol 54 (7) ◽  
pp. 685
Author(s):  
Д.В. Юрасов ◽  
Н.А. Байдакова ◽  
А.Н. Яблонский ◽  
А.В. Новиков
Keyword(s):  
Doping Level ◽  
Room Temperature ◽  
Carrier Lifetime ◽  
Growth Conditions ◽  
Published Data ◽  
Rapid Thermal Anneal ◽  
Time Resolved ◽  
Light Emitting ◽  
Pl Intensity ◽  
Time Resolved Photoluminescence

Light-emitting properties of Ge-on-Si(001) layers doped by Sb were studied by stationary and time-resolved photoluminescence (PL) at room temperature. It was obtained that the PL intensity of n-Ge/Si(001) structures is maximized when the doping level is close to the equilibrium solubility of Sb in Ge (~1019 cm-3) which is in accordance with the previously published data. Time-resolved studies of the direct-related PL signal have shown that both the donor density and the growth conditions of doped layer, in particular, the growth temperature influence the PL kinetics. It was obtained that the increase of doping level leads to the decrease of the characteristic carrier lifetime. Moreover, usage of low growth temperatures which is needed to form the doped n-Ge layers also results in shortening of the carrier lifetime as compared with Ge layers grown at high temperatures. It was found that rapid thermal anneal at proper conditions could partially compensate the above mentioned detrimental effects and lead to the increase of both the PL intensity and carrier lifetime.

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