The SiO2/Si Interface Probed With Positrons

1987 ◽  
Vol 105 ◽  
Author(s):  
Bent Nielsen ◽  
K. G. Lynn ◽  
T. C. Leung ◽  
D. O. Welch ◽  
G. Rubloff
Keyword(s):  
Heat Treatment ◽  
Elevated Temperature ◽  
Positron Annihilation ◽  
Positron Beam ◽  
The State ◽  
Open Volume ◽  
Variable Energy ◽  
Thermally Grown

AbstractThe effects of the heat treatment of Si covered with a thermally-grown ˜50 nm overlayer of SiO2 were probed by means of measurements of positron annihilation characteristics obtained with a variable-energy positron beam. From measurements at elevated temperature (˜500°C) it was observed that positrons implanted overlapping the SiO2/Si interface decay from a state with properties distinctively different from the state in Si and in SiO2. The nature of the annihilation characteristics indicates the presence of open volume defects.

POSITRON INTERACTION IN POLYMERS

2004 ◽  
Vol 19 (23) ◽  
pp. 3951-3959 ◽  
Author(s):  
CORINE BAS ◽  
N. DOMINIQUE ALBÉROLA ◽  
MARIE-FRANCE BARTHE ◽  
JÉRÉMIE De BAERDEMAEKER ◽  
CHARLES DAUWE
Keyword(s):  
Positron Annihilation ◽  
Chemical Structure ◽  
Positron Beam ◽  
Positron Annihilation Spectroscopy ◽  
Hole Size ◽  
Doppler Broadening ◽  
Positron Source ◽  
Positron Annihilation Lifetime ◽  
Doppler Broadening Spectra ◽  
Variable Energy

A series of dense copolyimide membranes was characterized using positron annihilation spectroscopy. The positron annihilation lifetime spectroscopy performed on film with a classical positron source gives informations on the positronium fraction formed and also on the hole size within the film. The Doppler broadening spectra (DBS) of the gamma annihilation rays coupled with a variable energy positron beam allow the microstructural analyses as a function of the film depth. Experimental data were also linked to the chemical structure of the polyimides. It was found that the presence of the fluorine atoms strongly affects the positron annihilitation process and especially the DBS responses.

Effect of Sintering on Defects in Yttria Stabilised Zirconia

2012 ◽  
Vol 733 ◽  
pp. 236-239 ◽  
Author(s):  
Ivan Procházka ◽  
Jakub Čížek ◽  
Oksana Melikhova ◽  
Wolfgang Anwand ◽  
Gerhard Brauer ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Subsurface Layer ◽  
Positron Beam ◽  
Annihilation Radiation ◽  
Strong Suppression ◽  
Slow Positron ◽  
Open Volume ◽  
Zirconia Nanopowders ◽  
Variable Energy

A variable energy slow positron beam was utilised to investigate depth dependent effects of sintering on the tetragonal yttria stabilised zirconia nanopowders. Positron implantation was combined with the determination of Doppler broadened profiles of annihilation radiation. The results are consistent with recent positron lifetime data showing that sintering at elevated temperatures leads to a disappearance of pores and a significant grain growth, which is demonstrated by a strong suppression of positronium formation and a substantial decrease in concentration of open volume defects at triple points, respectively, with increasing sintering temperature. An existence of a subsurface layer of a relatively high content of defects was shown in sintered samples and tentatively attributed to arise from a diffusion of open volume defects from the sample interior toward the surface or from a sintering-induced surface modification.

scholarly journals A new approach to near-surface positron annihilation analysis of ion irradiated ferritic alloys

2021 ◽  
Author(s):  
Vladimir Krsjak ◽  
Petr Hruška ◽  
Jarmila Degmova ◽  
Stanislav Sojak ◽  
Pavol Noga ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Ion Beam ◽  
Positron Beam ◽  
Ion Beam Irradiation ◽  
Near Surface ◽  
Slow Positron ◽  
New Approach ◽  
Ferritic Alloys ◽  
Positron Annihilation Lifetime ◽  
Variable Energy

The present work provides an innovative approach to the near-surface slow-positron-beam (SPB) study of structural materials exposed to ion-beam irradiation. This approach enables the use of variable-energy positron annihilation lifetime...

Hydrogen interaction with oxidized Si(111) probed with positrons

1989 ◽  
Vol 67 (8) ◽  
pp. 818-820 ◽  
Author(s):  
K. G. Lynn ◽  
Bent Nielsen ◽  
D. O. Welch
Keyword(s):  
Positron Annihilation ◽  
Momentum Distribution ◽  
Electron Pair ◽  
Positron Beam ◽  
Thermally Grown Oxide ◽  
Doppler Broadening ◽  
Hydrogen Binding ◽  
Hydrogen Interaction ◽  
Hydrogen Exposure ◽  
Variable Energy

A variable-energy positron beam was utilized to study the interface action of hydrogen with Si(111) covered by an ultrahigh-vacuum thermally grown oxide of 2–3 nm thickness. It was observed that positrons implanted at shallow depth (<100 nm) after diffusion are trapped either at the interface between the oxide and the Si or in the oxide. The positron-annihilation characteristics of these trapped positrons are found to be very sensitive to hydrogen exposure. The momentum distribution of the annihilating positron–electron pair, as observed in the Doppler broadening of the annihilation line, broadens considerably after exposure to hydrogen. The effect recovers after annealing at [Formula: see text], suggesting a hydrogen binding at the interface of ~3 ± 0.3 eV.

Vacancy Related Defects in Thin Film Pb(ZrTi)O3 Materials

1994 ◽  
Vol 361 ◽  
Author(s):  
A. Krishnan ◽  
D.J. Keeble ◽  
R. Ramesh ◽  
W.L. Warren ◽  
B.A. Tuttle ◽  
...  
Keyword(s):  
Thin Film ◽  
Laser Ablation ◽  
Positron Annihilation ◽  
Sol Gel ◽  
Ferroelectric Thin Film ◽  
Positron Beam ◽  
S Parameter ◽  
Pt Electrodes ◽  
Post Deposition ◽  
Variable Energy

ABSTRACTPositron annihilation techniques have been applied to characterize vacancy-related defects in ferroelectric thin film structures. Variable energy positron beam measurements were carried out on doped and undoped Pb(Zr,Ti)O3 (PZT) samples subjected to different post-deposition cool down and anneal conditions. The PZT was deposited by sol-gel with either with platinum or RuO2 electrodes, or by laser ablation with La0.5Sr0.5CoO3 electrodes. The RuO2 and La0.5Sr0.5CoO3 electrode samples showed a smaller S-parameter compared to those deposited with Pt electrodes consistent with an improved PZT layer quality. For laser ablated samples cooled in a reducing ambient an increase in S-parameter for both the PZT and La0.5Sr0.5CoO3 layers was observed indicating an increase in neutral or negatively charged open-volume defects.

Defect Detection in Fe-Cr Alloys with Positron Annihilation Doppler Broadening Spectroscopy

2012 ◽  
Vol 733 ◽  
pp. 270-273 ◽  
Author(s):  
Veronika Sabelová ◽  
Martin Petriska ◽  
Jana Veterníková ◽  
Vladimir Slugeň ◽  
Jarmila Degmová ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Positron Beam ◽  
Quantitative Information ◽  
Structural Defects ◽  
Doppler Broadening ◽  
Positron Energy ◽  
Open Volume ◽  
Order Of Magnitude ◽  
Radiation Induced ◽  
Induced Defects

Positron annihilation Doppler broadening spectroscopy (DBS) has been used for the detection of structural defects in Fe-9wt%Cr (Fe-9Cr) alloy in the as-prepared and implanted states. Defects were created by He and H ion implantation with a kinetic energy of 250 keV. DBS is a non-destructive method and is a unique tool for the observation of open volume defects like vacancies and vacancy clusters in solids. A positron beam with variable positron energy was used for the measurement of defect depth profiles up to 1.5 µm. The obtained results provide qualitative and semi-quantitative information about radiation induced defects and their chemical environment. Although the collision damage from helium implantation was one order of magnitude higher than for the case of hydrogen, the changes in S and W parameters are much less significant, probably due to considerably lower mobility of helium in the implanted materials, which results in helium capture by the created open volume defects.

Slow Positron Beam Probe for the ZnO/Silicone under Proton Irradiation

2008 ◽  
Vol 607 ◽  
pp. 108-110
Author(s):  
Ying Ping Hao ◽  
Hui Min Weng ◽  
Chun Dong Li ◽  
Wei Feng Guo ◽  
Jian Dang Liu ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Crosslink Density ◽  
Proton Irradiation ◽  
Diffusion Length ◽  
Effective Diffusion ◽  
Positron Beam ◽  
Coating System ◽  
Slow Positron ◽  
Silicone Coating ◽  
Variable Energy

The degradation of ZnO/Silicone coating system under 90keV proton irradiation varying from 5×1014cm-2 to 1×1016cm-2, was studied by slow positron annihilation spectrum. Effective diffusion length calculated by Variable energy positron fit (VEPFIT) shows a dramatically break in a dose of 1×1015cm-2. It is ascribed to the increase of crosslink density and decrease of free volume and hole during the proton irradiation. Furthermore, positron has shown a satisfying sensitivity in detecting the nano-scale defect on ZnO/Silicone system.

scholarly journals PLEPS: Pulsed low energy positron system

2015 ◽  
Vol 1 ◽  
Author(s):  
Werner Egger
Keyword(s):  
Positron Annihilation ◽  
Depth Profiling ◽  
Positron Beam ◽  
Low Energy ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Positron Annihilation Lifetime ◽  
Variable Energy

PLEPS, operated by the Universität der Bundeswehr München, located at NEPOMUC, is a unique tool for depth profiling of defects with positron annihilation lifetime spectroscopy using a pulsed positron beam of variable energy.

scholarly journals Positron Annihilation Spectroscopy in Material studies

2019 ◽  
Vol 29 (4) ◽  
pp. 501 ◽  
Author(s):  
P. Horodek ◽  
L. H. Khiem ◽  
K. Siemek ◽  
L. A. Tuyen ◽  
A. G. Kobets
Keyword(s):  
Positron Annihilation ◽  
Science And Technology ◽  
Nuclear Research ◽  
Positron Beam ◽  
Positron Annihilation Spectroscopy ◽  
Atomic Energy ◽  
Joint Institute ◽  
Experimental Techniques ◽  
Open Volume ◽  
Material Studies

Positron annihilation spectroscopy (PAS) is a method dedicated to detection of open-volume type of defects in materials. Nowadays, this technique is of a great interest due to the practical character of obtained results. New devices using monoenergetic positron beams are built. The paper presents the basics of PAS, a description of popular experimental techniques and their application on the basis of results obtained in the frame of collaboration between Joint Institute for Nuclear Research (JINR), Institute of Physics - Vietnamese Academy of Science and Technology (VAST) and Vietnam Atomic Energy Institute (Vinatom).. The positron beam with energy up to 35 keV and other apparatus for PAS studies are under operation in Dubna.

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