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.

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.

scholarly journals Study of Microvoids in High-Rate a-Si:H Using Positron Annihilation

1997 ◽  
Vol 467 ◽  
Author(s):  
X. Zou ◽  
D. P. Webb ◽  
S. H. Lin ◽  
Y. W. Lam ◽  
Y. C. Chan ◽  
...  
Keyword(s):  
Thin Films ◽  
Positron Annihilation ◽  
Surface Region ◽  
Positron Beam ◽  
High Rate ◽  
Doppler Broadening ◽  
Slow Positron ◽  
Depth Profiles ◽  
Vacancy Type Defect ◽  
Low Rate

ABSTRACTIn this paper, we have carried out the positron annihilation measurement on high-rate and low-rate a-Si:H thin films deposited by PECVD. By means of the slow positron beam Doppler-broadening technique, the depth profiles of microvoids in a-Si:H have been determined. We have also studied the vacancy-type defect in the surface region in high-rate grown a-Si:H, making comparison between high-rate and low-rate a-Si:H. By plotting S and W parameters in the (S, W) plane, we have shown that the vacancies in all of the high-rate and low-rate deposited intrinsic samples, and in differently doped low-rate samples are of the same nature.

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.

Temperature Dependence of Radiation Damage in ODS Steel Studied by Triple Beam Irradiation and Positron Annihilation Techniques

2017 ◽  
Vol 373 ◽  
pp. 91-95 ◽  
Author(s):  
Da Qing Yuan ◽  
Qiao Li Zhang ◽  
Ping Fan ◽  
Xian Ping Wang ◽  
Bin Long ◽  
...  
Keyword(s):  
Radiation Damage ◽  
Positron Annihilation ◽  
Ion Beam ◽  
Positron Beam ◽  
Doppler Broadening ◽  
Beam Irradiation ◽  
Single Beam ◽  
Positron Annihilation Lifetime ◽  
Ods Steel ◽  
S Parameter

The oxide dispersed strengthened (ODS) ferritic-martensitic steel was irradiated by 100MeV iron ion whose energy was degraded by using a Ta foil of 4 μm thick, 100 keV Hydrogen and 200 keV Helium at 480, 515, 550 and 580 °C. The irradiation fluences were 1×1016, 1.1×1015 and 6.8×1013/cm2, respectively for Fe, H and He. The techniques of positron annihilation lifetime and Doppler broadening of slow positron beam were utilized to examine the produced radiation damage. At 550 °C the maximal positron annihilation lifetime and S parameter of Doppler broadening were observed, implyin g tha t 550 °C is the pea k temperature of swelling. The S parameter and annihilation lifetime of the sample irradiated at 515 °C by the single Fe ion beam were smaller compared to the triple beam irradiation at the same temperature, implying that the triple beam irradiation caused more severe damage than the single beam irradiation.

A SYMMETRY BASED STUDY OF POSITRON ANNIHILATION SPECTRA

1995 ◽  
Vol 09 (28) ◽  
pp. 3667-3687 ◽  
Author(s):  
GH. ADAM ◽  
S. ADAM
Keyword(s):  
Single Crystals ◽  
Positron Annihilation ◽  
Momentum Distribution ◽  
Electron Pair ◽  
Annihilation Radiation ◽  
Two Dimensional ◽  
Fermi Surfaces ◽  
Piecewise Constant ◽  
Positron Spectroscopy ◽  
Line Analysis

We describe a method for off-line analysis of spectra measured by two-dimensional angular correlation of annihilation radiation [Formula: see text] positron spectroscopy. The method takes into account, at all its stages, two salient data features: the piecewise constant discretization of the [Formula: see text] physical momentum distribution into square pixels, performed by the setup, and the occurrence of a characteristic [Formula: see text] projected symmetry of the positron–electron pair momentum distribution. Several validating criteria are derived which secure significantly increased reliability of the output. The method is tested on [Formula: see text] spectra measured on (R)Ba 2 Cu 3 O 7−δ( R123 ; R= Y, Dy) single crystals. It resolves ridge Fermi surfaces [Formula: see text] up to 3rd Umklapp components on both kinds of R123 spectra. Moreover, on a c-axis-projected Y123 spectrum, measured at 300 K, it resolves a small but clear signature of the pillbox [Formula: see text] at the S point of the first Brillouin zone as well.

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...

A Study of Defects in Czochralski-Grown Silicon by Positron Annihilation Spectroscopy

1992 ◽  
Vol 262 ◽  
Author(s):  
S. C. Sharma ◽  
N. Hozhabri ◽  
R. G. Hyer ◽  
T. Hossain ◽  
S. Kim ◽  
...  
Keyword(s):  
Positron Lifetime ◽  
Single Crystal Silicon ◽  
Positron Beam ◽  
Positron Annihilation Spectroscopy ◽  
Doppler Broadening ◽  
Crystal Silicon ◽  
Different Depths ◽  
Positron Lifetime Spectroscopy ◽  
Doppler Broadening Spectra ◽  
Variable Energy

ABSTRACTWe have studied defects in Cz-grown single crystal silicon by utilizing a variable energy positron beam and positron lifetime spectroscopy in conjunction with surface photovoltage measurements. We present results for the depth profile of defects obtained from the Doppler broadening spectra measured by implanting variable energy positrons at different depths ranging from the surface down to ∼ 1 /xm deep. We have also measured positron lifetime spectra at different locations on a wafer and have obtained a radial variation in the density of the vacancy-type defects.

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.

Cu gettering in Si cavities observed by Positron Annihilation Doppler Broadening

2000 ◽  
Vol 647 ◽  
Author(s):  
H. Schut ◽  
A. van Veen ◽  
S.W.H. Eijt
Keyword(s):  
Surface Layer ◽  
Positron Annihilation ◽  
Internal Surface ◽  
Positron Beam ◽  
Implantation Dose ◽  
Doppler Broadening ◽  
Higher Doses ◽  
Cluster Points

AbstractIn this study we present the results of Positron Beam Annihilation (PBA) experiments on the gettering of copper in Cz-Si implanted with 33 keV He+ ions with doses ranging from 0.5 to 3× 1016cm−2 followed by an anneal treatment at 1100 K under N2 ambient. For the higher doses this yields a sub-surface layer containing nanometer sized cavities. Copper is introduced into these cavities by diffusing from the backside of the wafer at 1000 K, again under N2 ambient. Mapping of the S and W Doppler broadening parameters, with the implantation dose as running parameter, shows the formation of cavities. After the Cu in-diffusion the change in the values of the characteristic S-W cluster points clearly demonstrates the arrival of Cu at the internal surface of the cavities.

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