Evaluation of Vacancy-Type Defects in Simox Substrates by a Slow Positron Beam and a Pulsed Positron Beam

1992 ◽  
Vol 262 ◽  
Author(s):  
H. Kametani ◽  
H. Akiyama ◽  
Y. Yamaguchi ◽  
M. Koumaru ◽  
L. Wei ◽  
...  
Keyword(s):  
Positron Lifetime ◽  
Silicon Layer ◽  
Positron Beam ◽  
High Dose ◽  
Positron Energy ◽  
Slow Positron ◽  
Depth Profiles ◽  
Positron Beams ◽  
Non Destructive ◽  
Incident Positron

ABSTRACTSlow/monoenergetic positron beams and pulsed positron beams have been used as a non-destructive probe to investigate vacancy-type defects in SIMOX substrates which were formed by high - dose oxygen implantation and high-temperature annealing. To obtain depth profiles of vacancy-type defects, a positron beam in the 0–30keV energy range was used. Doppler broadened annihilation spectrum and positron lifetime were measured as a function of incident positron energy. These measurements show the following results; vacancy -type defects exist near the surface of the top silicon layer even if the specimen was analyzed as defect -free Silicon by XTEM, and in the case of the as-implanted specimen, cavities in diameter of about 50–200A are created in the top silicon layer and they include high pressure gases.

Slow Positron Studies in Polymers

2010 ◽  
Vol 307 ◽  
pp. 85-92
Author(s):  
S.B. Shrivastava ◽  
Aman Deep Acharya ◽  
R. Sharma
Keyword(s):  
Positron Lifetime ◽  
Hole Concentration ◽  
Low Energy ◽  
Positronium Formation ◽  
Positron Energy ◽  
Slow Positron ◽  
Polymeric Surface ◽  
S Parameter ◽  
Free Volume Hole ◽  
Incident Positron

The diffusion trapping model has been applied to slow positron annihilation in He+ irradiated polystyrene and polystyrene – polystyrene bilayers. The S-parameter and the positron lifetime have been calculated as a function of the incident positron energy. The effect of the fluence upon the nature of the S-parameter curve has been discussed. It has been found that a change in fluence affects positronium formation. The transition rate for surface to positronium formation has been found to be dependent upon the fluence and the atomic number of the irradiated ion. The lifetime results show that, at low energy, the o-Ps annihilates mainly at the polymeric surface. The free volume hole concentration is found to decrease at low energy, and becomes constant at higher energies.

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.

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.

Positron spectroscopy of bulk and near-surface defects in semiconductors

1989 ◽  
Vol 67 (8) ◽  
pp. 813-817
Author(s):  
P. Hautojārvi
Keyword(s):  
Positron Annihilation ◽  
Positron Lifetime ◽  
Surface Defects ◽  
Positron Beam ◽  
Near Surface ◽  
Slow Positron ◽  
Positron Spectroscopy ◽  
Positron Lifetime Spectroscopy ◽  
Defects In Semiconductors ◽  
Ion Implanted

The use of positron annihilation to study defects in semiconductors is discussed. Positron-lifetime spectroscopy reveals As vacancies in as-grown GaAs and gives information on ionization levels. The vacancy profiles in ion-implanted Si are investigated by slow positron beam.

scholarly journals Toward a European Network of Positron Laboratories

Nukleonika ◽  
2015 ◽  
Vol 60 (4) ◽  
pp. 733-739 ◽  
Author(s):  
Grzegorz P. Karwasz ◽  
Roberto S. Brusa ◽  
Werner Egger ◽  
Olga V. Ogorodnikova
Keyword(s):  
Water Vapor ◽  
Positron Lifetime ◽  
Complex Dynamics ◽  
Positron Beam ◽  
Doppler Broadening ◽  
European Network ◽  
Lifetime Measurements ◽  
Positron Beams ◽  
Positron Lifetimes ◽  
Material Studies

AbstractSome applications of controlled-energy positron beams in material studies are discussed. In porous organic polysilicates, measurements of 3γ annihilation by Doppler broadening (DB) method at the Trento University allowed to trace pore closing and filling by water vapor. In silicon coimplanted by He+and H+, DB data combined with positron lifetime measurements at the München pulsed positron beam allowed to explain Si blistering. Presently measured samples of W for applications in thermonuclear reactors, irradiated by W+and electrons, show vast changes of positron lifetimes, indicating complex dynamics of defects.

A slow positron lifetime study of the annealing behaviour of an amorphous silicon layer grown by MBE

1995 ◽  
Vol 61 (1) ◽  
pp. 71-74
Author(s):  
J. St�rmer ◽  
P. Willutzki ◽  
D. T. Britton ◽  
G. K�gel ◽  
W. Triftsh�user ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Positron Lifetime ◽  
Silicon Layer ◽  
Slow Positron ◽  
Annealing Behaviour

Slow positron beam design notes

1982 ◽  
Vol 60 (4) ◽  
pp. 551-557 ◽  
Author(s):  
K. F. Canter ◽  
A. P. Mills Jr.
Keyword(s):  
Figure Of Merit ◽  
Transverse Energy ◽  
High Vacuum ◽  
Positron Beam ◽  
Ultra High Vacuum ◽  
High Flux ◽  
Slow Positron ◽  
Beam Design ◽  
Positron Beams ◽  
Conversion Efficiencies

Recent methods of producing high flux. (105–106) s−1 slow positron beams are briefly reviewed. Currently, slow positron beams are produced most efficiently using a single crystal Cu(111) + S backscatter geometry moderator for ultra-high vacuum (UHV) conditions and an annealed W-vane converter for non-UHV conditions. The respective fast positron to slow positron conversion efficiencies for the Cu(111) + S and W-vane converters are (9 ± 3) × 10−4 and (1.2 ± 0.2) × 10−4. A new figure of merit, the "normalized brightness-per-volt", for converters is introduced which takes into account the transverse energy spread as well as the conversion efficiency. The importance of the normalized-brightness-per-volt in beam design and future methods to improve this figure of merit are discussed.

Diffusion Processes in the Sintering of Zirconia-Based Nanomaterials

2013 ◽  
Vol 26 ◽  
pp. 25-31
Author(s):  
Oksana Melikhova ◽  
Jakub Čížek ◽  
Ivan Procházka ◽  
Wolfgang Anwand ◽  
Tetyana E. Konstantinova ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Elevated Temperatures ◽  
Diffusion Processes ◽  
High Sensitivity ◽  
Positron Beam ◽  
Positron Annihilation Spectroscopy ◽  
Atomic Scale ◽  
Slow Positron ◽  
Co Precipitation ◽  
Non Destructive

In the present work, zirconia-based nanomaterials with various stabilizers were prepared by a co-precipitation technique. Defects in these nanomaterials were characterized by positron annihilation spectroscopy which is a non-destructive technique with a high sensitivity to open volume defects and atomic scale resolution. It was found that zirconia-based nanomaterials contain vacancies and also nanoscale and meso-scale pores. Diffusion processes which occur in the nanomaterials sintered at elevated temperatures were investigated by depth sensitive positron annihilation studies on a variable energy slow positron beam. It was found that sintering causes intensive grain growth and residual porosity is removed from samples by diffusion to the surface.

Slow Positron Annihilation in Ion-Implanted Silicon

2008 ◽  
Vol 280-281 ◽  
pp. 21-28 ◽  
Author(s):  
Girjesh Singh ◽  
S.B. Shrivastava ◽  
M.H. Rathore
Keyword(s):  
Positron Annihilation ◽  
Shape Parameter ◽  
Positron Energy ◽  
Slow Positron ◽  
Vacancy Clusters ◽  
S Parameter ◽  
Trapping Model ◽  
Line Shape Parameter ◽  
Incident Positron ◽  
Ion Implanted

The mechanism of slow positron annihilation in ion-implanted Si has been discussed in terms of the Diffusion-Trapping model (DTM). The trapping of positron has been considered in native vacancies (monovacancies) and ion induced vacancies i.e. vacancy clusters. The model has been used to calculate the Doppler broadening line shape parameter (S-parameter) as a function of incident positron energy for different ion-implanted Si. It has been found that at lower energies the monovacancies and vacancy clusters both contribute to the S-parameter while, with the increase in positron energy the vacancy clusters are reduced. The S-parameter is found to be dependent on the fluency of the implanted ions.

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