Fast photoluminescence decay processes of doped ZnS phosphors at low temperature

2006 ◽  
Vol 382 (1-2) ◽  
pp. 38-44 ◽  
Author(s):  
H.S. Bhatti ◽  
Rajesh Sharma ◽  
N.K. Verma
Keyword(s):  
Low Temperature ◽  
Photoluminescence Decay ◽  
Zns Phosphors

scholarly journals Quantum-Confined Stark Effect and Recombination Dynamics of Spatially Indirect Excitons in MBE-Grown GaN-AlGaN Quantum Wells

1999 ◽  
Vol 4 (S1) ◽  
pp. 375-380 ◽  
Author(s):  
Pierre Lefebvre ◽  
Bernard Gil ◽  
Jacques Allègre ◽  
Henry Mathieu ◽  
Nicolas Grandjean ◽  
...  
Keyword(s):  
Low Temperature ◽  
Quantum Wells ◽  
Electric Fields ◽  
Stark Effect ◽  
Quantum Confined Stark Effect ◽  
Indirect Excitons ◽  
Photoluminescence Decay ◽  
Decay Times ◽  
Low Temperature Photoluminescence ◽  
Recombination Dynamics

We analyze the low-temperature photoluminescence decay times, for a series of MBE-grown samples embedding GaN-AlGaN quantum wells. We investigate a variety of configurations in terms of well widths, barrier widths and overall strain states. We find that not only the wells but also the barriers are submitted to large built-in electric fields. In the case of narrow barriers (5 nm), these fields favor the nonradiative escape of carriers from narrow wells into wider wells. When all wells have the same width, the field in such narrow barriers allow us to observe the recombination of long-lived “inter-well” excitons at energies close to those of the short-lived “intra-well” excitons. Our results also prove that the energies and the dynamics of excitonic recombinations depend on the parameters of the heterostructures in a complicated way, due to the interplay of piezoelectric and spontaneous polarizations.

Decay Measurements of Free and Bound Exciton Recombination in Doped GaAs/GaAIAs Quantum Wells

1989 ◽  
Vol 163 ◽  
Author(s):  
J.P. Bergman ◽  
P.O. Holtz ◽  
B. Monemar ◽  
M. Sundaram ◽  
J.L Merz ◽  
...  
Keyword(s):  
Low Temperature ◽  
Quantum Wells ◽  
Temperature Dependence ◽  
Decay Time ◽  
Free Exciton ◽  
Temperature Decay ◽  
Photoluminescence Decay ◽  
Decay Times ◽  
Exciton Recombination

AbstractIn this study we present photoluminescence decay measurements of free exciton (FE) and bound exciton (BE) recombination in doped GaAs/AIGaAs quantum wells (QW). It is found that the FE decay time is reduced in the doped QW’s compared to similar undoped samples. The low temperature decay time of the BE is slightly longer than for the FE, with BE decay times from 300 to 600 ps for well widths of 50 to 150 Å, respectively. It is also found that the observed decay of the BE is strongly influenced by the decay time of the FE. This is especially observed in the similarity of the temperature dependence for the FE and BE decay time.

Quantum-Confined Stark Effect and Recombination Dynamics of Spatially Indirect Excitons in Mbe-Grown GaN-AlGaN Quantum Wells

1998 ◽  
Vol 537 ◽  
Author(s):  
Pierre Lefebvre ◽  
Bernard Gil ◽  
Jacques Allègre ◽  
Henry Mathieu ◽  
Nicolas Grandjean ◽  
...  
Keyword(s):  
Low Temperature ◽  
Quantum Wells ◽  
Electric Fields ◽  
Stark Effect ◽  
Quantum Confined Stark Effect ◽  
Indirect Excitons ◽  
Photoluminescence Decay ◽  
Decay Times ◽  
Low Temperature Photoluminescence ◽  
Recombination Dynamics

AbstractWe analyze the low-temperature photoluminescence decay times, for a series of MBE-grown samples embedding GaN-AlGaN quantum wells. We investigate a variety of configurations in terms of well widths, barrier widths and overall strain states. We find that not only the wells but also the barriers are submitted to large built-in electric fields. In the case of narrow barriers (5 um), these fields favor the nonradiative escape of carriers from narrow wells into wider wells. When all wells have the same width, the field in such narrow barriers allow us to observe the recombination of long-lived “inter-well” excitons at energies close to those of the short-lived “intra-well” excitons. Our results also prove that the energies and the dynamics of excitonic recombinations depend on the parameters of the heterostructures in a complicated way, due to the interplay of piezoelectric and spontaneous polarizations.

Ultrafast photoluminescence decay in low-temperature MOCVD-grown InxGa1-xAs

1994 ◽  
Vol 9 (7) ◽  
pp. 1382-1386 ◽  
Author(s):  
A Krotkus ◽  
S Marcinkevicius ◽  
V Pasiskevicius ◽  
U Olin
Keyword(s):  
Low Temperature ◽  
Photoluminescence Decay

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

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