Radiative Versus Nonradiative Decay Processes in Germanium Nanocrystals Probed by Time-resolved Photoluminescence Spectroscopy

2005 ◽  
Vol 864 ◽  
Author(s):  
P. K. Giri ◽  
R. Kesavamoorthy ◽  
B. K. Panigrahi ◽  
K.G.M. Nair
Keyword(s):  
Steady State ◽  
Time Constant ◽  
Defect Density ◽  
Ion Beam ◽  
Radiative Lifetime ◽  
Time Resolved ◽  
Pl Emission ◽  
Induced Defects ◽  
Time Resolved Photoluminescence ◽  
Ge Nanocrystals

AbstractGe nanocrystals (NCs) of diameter 4–13 nm are grown embedded in a thermally grown SiO2 layer by Ge ion implantation and subsequent annealing. Steady state and time-resolved photoluminescence (PL) studies are performed on these embedded Ge nanocrystals to understand the origin of the PL emission at room temperature. Steady state PL spectra show a broad peak consisting of a peak at ∼2.1 eV originating from Ge NCs and another peak at ∼2.3 eV arising from ion-beam induced defects in the Ge/SiO2 interface. Time-resolved PL studies reveal double exponential decay dynamics of the PL emission on the nanoseconds time scale. The faster component of the decay with large amplitude and having a time constant τ1∼3.1 ns is attributed to the nonradiative lifetime, since the time constant reduces with increasing defect density. The slower component with time constant τ2∼10 ns is attributed to radiative recombination at the Ge NCs. These results are in close agreement with the theoretically predicted radiative lifetime for small Ge NCs.

Steady state and time-resolved photoluminescence properties of alternating polyfluorene copolymers

2003 ◽  
Vol 135-136 ◽  
pp. 387-388 ◽  
Author(s):  
A. Charas ◽  
J. Morgado ◽  
L. Alcácer ◽  
J.M.G. Martinho ◽  
F. Cacialli
Keyword(s):  
Steady State ◽  
Photoluminescence Properties ◽  
Time Resolved ◽  
Time Resolved Photoluminescence

UNDERSTANDING ULTRAVIOLET EMITTER PERFORMANCE USING INTENSITY DEPENDENT TIME-RESOLVED PHOTOLUMINESCENCE

2007 ◽  
Vol 17 (01) ◽  
pp. 179-188 ◽  
Author(s):  
MICHAEL WRABACK ◽  
GREGORY A. GARRETT ◽  
ANAND V. SAMPATH ◽  
PAUL H. SHEN
Keyword(s):  
Radiative Lifetime ◽  
Active Regions ◽  
Pump Intensity ◽  
Performance Comparison ◽  
Nonradiative Recombination ◽  
Extended Defects ◽  
Light Emitters ◽  
Time Resolved ◽  
Photoluminescence Studies ◽  
Time Resolved Photoluminescence

Time-resolved photoluminescence studies of nitride semiconductors and ultraviolet light emitters comprised of these materials are performed as a function of pump intensity as a means of understanding and evaluating device performance. Comparison of time-resolved photoluminescence (TRPL) on UV LED wafers prior to fabrication with subsequent device testing indicate that the best performance is attained from active regions that exhibit both reduced nonradiative recombination due to saturation of traps associated with point and extended defects and concomitant lowering of radiative lifetime with increasing carrier density. Similar behavior is observed in optically pumped UV lasers. Temperature and intensity dependent TRPL measurements on a new material, AlGaN containing nanoscale compositional inhomogeneities (NCI), show that it inherently combines inhibition of nonradiative recombination with reduction of radiative lifetime, providing a potentially higher efficiency UV emitter active region.

Tuning the excited-state deactivation pathways of dinuclear ruthenium(ii) 2,2′-bipyridine complexes through bridging ligand design

2020 ◽  
Vol 49 (24) ◽  
pp. 8096-8106 ◽  
Author(s):  
Simon Cerfontaine ◽  
Ludovic Troian-Gautier ◽  
Sara A. M. Wehlin ◽  
Frédérique Loiseau ◽  
Emilie Cauët ◽  
...  
Keyword(s):  
Excited State ◽  
Steady State ◽  
Variable Temperature ◽  
Ligand Design ◽  
Binuclear Complexes ◽  
Time Resolved ◽  
Bridging Ligand ◽  
Dinuclear Ruthenium ◽  
Photophysical Study ◽  
Time Resolved Photoluminescence

A detailed photophysical study of binuclear complexes was performed using steady-state and time-resolved photoluminescence measurements at variable temperature. The results were compared with the prototypical [Ru(bpy)3]2+.

Steady state and time resolved photoluminescence properties of CuInS2/ZnS quantum dots in solutions and in solid films

2015 ◽  
Vol 167 ◽  
pp. 333-338 ◽  
Author(s):  
Nikolaos Droseros ◽  
Kostas Seintis ◽  
Mihalis Fakis ◽  
Spiros Gardelis ◽  
Androula G. Nassiopoulou
Keyword(s):  
Quantum Dots ◽  
Steady State ◽  
Photoluminescence Properties ◽  
Time Resolved ◽  
Solid Films ◽  
Time Resolved Photoluminescence

Saturation of Metastable-Defect Density in a-Si:H

1990 ◽  
Vol 192 ◽  
Author(s):  
David Redfield ◽  
Richard H. Bube
Keyword(s):  
Steady State ◽  
Defect Density ◽  
Atomic Model ◽  
Transient Responses ◽  
Induced Defects ◽  
Metastable Defect

ABSTRACTThe existence of saturation (or steady state) in the density of light-induced defects in amorphous Si:H is shown to have major importance for the interpretation of the nature and origin of these defects. First, a number of characteristics of the steady-state and transient responses to light and temperature are described and contrasted. These lead to the conclusion that the saturation value is the only useful criterion of the number of defects in these materials. We then describe a new atomic model for defects, unifying both dopant-induced and light-induced defects. This model invokes foreign atoms in defects, and saturation reflects the limitation imposed by the numbers of such atoms. Many other observed properties of defects are explained by this model.

Time-Resolved Photoluminescence of GaN / Ga0.93Al0 .07N Quantum Wells

1997 ◽  
Vol 482 ◽  
Author(s):  
P. Lefebvre ◽  
J. Allègre ◽  
B. Gil ◽  
A. Kavokine ◽  
H. Mathieu ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Radiative Lifetime ◽  
Temperature Limit ◽  
Multiple Quantum ◽  
Carrier Localization ◽  
Substantial Variation ◽  
Time Resolved ◽  
Potential Fluctuations ◽  
Alloy Disorder ◽  
Time Resolved Photoluminescence

AbstractThe recombination dynamics of excitons in GaN / Ga0.93Al0.07N multiple quantum wells is studied versus lattice temperature. The average decay time of photoluminescence measured at 8K is of ∼330 ps, with a substantial variation of times within the emission line. This is interpreted in terms of carrier localization due to alloy disorder and to well width and depth variations. The radiative lifetime τr of excitons in the wells is found to increase linearly with temperature, with ∂τr / ∂T = 20.5 ± 0.7 ps.K−1. The radiative lifetime of free excitons in the low-temperature limit is deduced to be 2.4 ps, consistent with a longitudinal-transverse splitting ћωLT in GaN of 0.6 meV, in excellent agreement with recent estimations. The ratio of the lifetimes of localized and free excitons is found coherent with the picture of electrons and holes independently localized on short-range defects, instead of excitons localized as a whole on long-range potential fluctuations.

Improve Persistent Luminescence in Pressure-tuned CsPbBr3 Nanocrystals by Ce3+ Doping

2021 ◽  
Author(s):  
Bao Liu ◽  
Meng Tian ◽  
Yang Gao ◽  
Pengyu Zhou ◽  
Kailin Chi ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Steady State ◽  
Photoluminescence Spectroscopy ◽  
Persistent Luminescence ◽  
Time Resolved ◽  
Novel Strategy ◽  
Time Resolved Photoluminescence ◽  
Kinetics Of

The pressure-dependent photoluminescence kinetics of CsPbBr3:Ce quantum dots was investigated by steady-state and time-resolved photoluminescence spectroscopy. Here, we propose a novel strategy to improve the persistent luminescence of CsPbBr3 quantum...

Defect Saturation in a-SiGe:H(F) Alloys

1992 ◽  
Vol 258 ◽  
Author(s):  
N.W. Wang ◽  
P.A. Morin ◽  
V. Chu ◽  
S. Wagner
Keyword(s):  
Steady State ◽  
Low Temperature ◽  
Light Intensity ◽  
Carrier Concentration ◽  
Thermal Annealing ◽  
Defect Density ◽  
High Light Intensity ◽  
High Light ◽  
The Other ◽  
Induced Defects

ABSTRACTIt is a question as yet unresolved whether the density of light-induced defects in a-Si:H reaches a saturated value that cannot fundamentally be exceeded, or whether the defect density is in all conditions a steady-state value that reflects carrier concentration and temperature. In our experiments on a-Si:H we have observed defect saturation at low temperature and high light intensity; on the other hand, data exhibiting no saturation have also been published. To learn more about this question we have carried out saturation experiments on a-SiGe:H(F) alloys. These alloys have lower defect freeze-in temperatures than a-Si:H and, presumably, lower annealing energies. Therefore, saturation should be more difficult to achieve in the alloys than in a-Si:H.We have studied saturation for a-SiGe:H(F) samples to temperatures above the onset of thermal annealing and have observed that its behavior is similar to that seen in a-Si:H.

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