Defects Introduced by Low Dose Be-Implantation Probed by a Monoenergetic Positron Beam

1992 ◽  
Vol 262 ◽  
Author(s):  
A. Uedono ◽  
Y. Ujihira ◽  
L. Wei ◽  
Y. Tabuki ◽  
S. Tanigawa ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Positron Annihilation ◽  
Low Dose ◽  
Positron Beam ◽  
Doppler Broadening ◽  
Positron Energy ◽  
P Type ◽  
Incident Positron ◽  
Depth Distributions

ABSTRACTVacancy-type defects in 60-keV Be+-implanted GaAs and InP were studied by a monoenergetic positron beam. The depth distributions of vacancy-type defects were obtained from measurements of Doppler broadening profiles of the positron annihilation as a function of incident positron energy. Vacancy-type defects introduced by ion implantation were observed in n-type GaAs. For p-type GaAs, however, this was not the case. This can be attributed to the recombination of vacancy-type defects and pre-existed interstitial-type defects in p-type GaAs. The defects induced by ion implantation in InP were also studied.

Defect Formation by Ion Implantation in Cz-Si Studied by a Monoenergetic Positron Beam

1992 ◽  
Vol 262 ◽  
Author(s):  
A. Uedono ◽  
Y. Ujihira ◽  
L. Wei ◽  
Y. Tabuki ◽  
S. Tanigawa ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Ion Implantation ◽  
Defect Formation ◽  
Positron Beam ◽  
Low Energy ◽  
Doppler Broadening ◽  
Positron Energy ◽  
Annealing Experiments ◽  
Incident Positron ◽  
Ion Implanted

ABSTRACTVacancy-type defects in ion implanted Si were studied by a monoenergetic positron beam. The depth-distributions of the defects were obtained from measurements of Doppler broadening profiles of the positron annihilation as a function of incident positron energy. The results showed that a size of vacany-clusters introduced by 150-keV P+-ion implantation was found to be smaller than that introduced by 2-MeV P+-ion implantation. This was attributed to an overlap of collision cascades in low-energy (150 keV) ion implanted specimens. From isochronal annealing experiments for 80-keV B+- and 150-keV P+-ion implanted specimens, the defected region was removed by 1200 °C annealing, however, for 2-MeV P+-implanted specimen, two-types of oxygen-vacancy complexes were found to coexist even after 1200 °C annealing.

The Lack of Trapping Centers for Positrons at the Interface of W/Si System and the Investigation of the Depletion Layer in the Schottky Barrier by Positrons as Test Charge Simulating Holes

1992 ◽  
Vol 262 ◽  
Author(s):  
S. Tanigawa ◽  
Y. Tabuki ◽  
L. Wei ◽  
K. Hinode ◽  
N. Kobayashi ◽  
...  
Keyword(s):  
Electric Field ◽  
Schottky Barrier ◽  
Positron Beam ◽  
Interfacial Phenomena ◽  
Doppler Broadening ◽  
Dc Magnetron Sputtering ◽  
Positron Energy ◽  
Test Charge ◽  
P Type ◽  
Incident Positron

ABSTRACTInterfacial phenomena in the W-Si systems were studied by a monoenergetic positron beam. Doppler broadening profiles of the positron annihilation were measured as a function of incident positron energy. Tungsten thin films of 100 nm in thickness were deposited on p-type, 10 »cm Cz-grown Si wafers with (100) orientation by the DC magnetron sputtering method. Specimens were annealed at various temperatures in order to form suicides. It was found that the position of the interface of both W/Si and W silicide/Si is very different from the position expected from a simple situation neglecting the effect of electric field on the diffusion of positrons. This fact arouse the utility of positrons as a test charge to probe directly the electric field gradient in the Schottky barrier.

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.

Resonant Positron Annihilation on Molecules

2008 ◽  
Vol 607 ◽  
pp. 9-16 ◽  
Author(s):  
J.A. Young ◽  
C.M. Surko
Keyword(s):  
Positron Annihilation ◽  
Binding Energies ◽  
Current Understanding ◽  
Positronium Atom ◽  
Feshbach Resonances ◽  
Positron Energy ◽  
Incident Positron

At incident positron energies below the threshold for positronium atom formation, there are many cases in which annihilation rates for molecules are far in excess of that possible on the basis of simple two-body collisions. We now understand that this phenomenon is due to positron attachment to molecules mediated by vibrational Feshbach resonances. The attachment enhances greatly the overlap of the positron with molecular electrons and hence increases the probability of annihilation. Furthermore, measurements of the annihilation spectra as a function of incident positron energy provide a means of measuring positron-molecule binding energies. In this paper we present an overview of our current understanding of this process, highlighting key results and discussing outstanding issues that remain to be explained.

Ion implantation of58Co for positron-annihilation Doppler-broadening measurements

1981 ◽  
Vol 24 (1) ◽  
pp. 67-69 ◽  
Author(s):  
M. J. Fluss ◽  
M. K. Chason ◽  
J. L. Lerner ◽  
D. G. Legnini ◽  
L. C. Smedskjaer
Keyword(s):  
Ion Implantation ◽  
Positron Annihilation ◽  
Doppler Broadening

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.

Ortho-Positronium Reemission Yield and Energy in Surfactant-Templated Mesoporous Silica Films

2008 ◽  
Vol 607 ◽  
pp. 30-33 ◽  
Author(s):  
Laszlo Lizkay ◽  
C. Corbel ◽  
P. Perez ◽  
P. Desgardin ◽  
Marie France Barthe ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Pore Size ◽  
Positron Annihilation ◽  
Time Of Flight ◽  
Positron Beam ◽  
High Porosity ◽  
Silica Layer ◽  
Silica Films ◽  
Gamma Energy ◽  
Positron Energy

Positron annihilation gamma energy distribution, lifetime spectroscopy and time-of-flight method were used to study surfactant-templated mesoporous silica films deposited on glass. The lifetime depth profiling was correlated to Doppler broadening and 3γ annihilation fraction measurements to determine the annihilation characteristics inside the films. A set of consistent fingerprints for positronium annihilation, o-Ps reemission into vacuum, and pore size was directly determined. The lifetime measurements were performed in reflection mode with a specially designed lifetime spectrometer mounted on a slow positron beam system. The intensity of the 142 ns vacuum lifetime component was recorded as a function of the energy of the positron beam. In a film with high porosity a reemission efficiency of as high as 40 % was found at low positron energy. Positron lifetime in samples capped by a thin silica layer was used to determine the pore size. The energy of the reemitted o-Ps fraction was measured by a time-of-flight detector, mounted on the same system, allowing determination of both o-Ps re-emission efficiency and energy in the same sample. We demonstrate the potential of the simultaneous use of different positron annihilation techniques in the study of thin porous films.

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.

Positronium Molecule Formation on Al (111)a

2008 ◽  
Vol 607 ◽  
pp. 22-24
Author(s):  
S.H.M. Deng ◽  
D.B. Cassidy ◽  
A.P. Mills
Keyword(s):  
Single Crystal ◽  
Positron Annihilation ◽  
Positron Beam ◽  
Single Shot ◽  
Beam Density ◽  
Positron Annihilation Lifetime ◽  
Molecule Formation ◽  
Positronium Lifetime ◽  
Positronium Molecule ◽  
Incident Positron

A single crystal Al (111) sample cleaned by repeated cycles of ion bombardment and annealing was irradiated by a subnanosecond high density positron beam [1] and the resulting positronium lifetime spectra were measured using single shot positron annihilation lifetime spectroscopy (SSPALS) [2]. We observed the amount of positronium emitted dependence on the incident positron beam density, which indicates the formation of positronium molecules (Ps2) at the Al (111) surface [3]. The Ps2 formation probability appears to be extremely sensitive to surface contamination and further experiments under improved vacuum conditions are planned to clarify this effect.

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