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.

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 FACILITIES FOR NANO MATERIALS EXAMINATION AT THE PULSTAR REACTOR

2021 ◽  
Vol 247 ◽  
pp. 08012
Author(s):  
A. I. Hawari ◽  
M. Liu ◽  
Q. Cai
Keyword(s):  
Positron Annihilation ◽  
Soft Matter ◽  
Single Crystal Silicon ◽  
Nuclear Research ◽  
Positron Beam ◽  
Positron Annihilation Spectroscopy ◽  
Distribution Functions ◽  
Crystal Silicon ◽  
Positron Annihilation Lifetime ◽  
The Us

The PULSTAR is a 1-MWth nuclear research reactor located at North Carolina State University. It is fueled by uranium dioxide assemblies enriched to 4% or 6% in U-235 and is currently under licensing for operation at 2-MWth power. The PULSTAR is a center for irradiation testing and pre/post irradiation examination of materials. Among its unique capabilities are positron annihilation spectroscopy (PAS) and neutron powder diffraction (NPD) facilities. The PAS facility provides an intense positron beam reaching 6 × 108 e+/s, which drives two spectrometers; the e+-PAS and the Ps-PAS, used for studies of defects in thin film materials. A Na-22 bulk PAS system is also operational, which is used for studying millimeter scale materials. All spectrometers are capable of performing Doppler Broadening Spectroscopy (DBS) and Positron Annihilation Lifetime Spectroscopy (PALS). To date, the PAS systems have been used to characterize various materials (unirradiated and irradiated) that include graphite, soft matter, and metal-organic frameworks (MOF). The NPD facility uses a double focusing single crystal silicon rotating monochromator producing neutron beams with different energies. A position sensitive detection bank covers a scattering angle of 5°-125°. The facility is used in the examination of unirradiated and irradiated materials including graphitic materials, magnetic materials without rare-earth elements, and anode materials used in lithium batteries. The collected diffraction patterns can be processed to produce atomic pair distribution functions. The PAS and NPD facilities are available through user programs including the US DOE’s Nuclear Science User Facilities (NSUF) and the US NSF’s Research Triangle Nanotechnology Network (RTNN).

Positron Annihilation Spectroscopy of Defects in Commercially Pure Titanium Saturated with Hydrogen

2014 ◽  
Vol 880 ◽  
pp. 134-140 ◽  
Author(s):  
Roman S. Laptev ◽  
Yuriy S. Bordulev ◽  
Viktor N. Kudiiarov ◽  
Andrey M. Lider ◽  
Georgy V. Garanin
Keyword(s):  
Gas Phase ◽  
Positron Lifetime ◽  
Pure Titanium ◽  
Metal Structure ◽  
Positron Annihilation Spectroscopy ◽  
Doppler Broadening ◽  
Commercially Pure Titanium ◽  
Commercially Pure ◽  
Hydrogen Interaction ◽  
Positron Lifetime Spectroscopy

The experimental study of the structure of commercially pure titanium after saturation with hydrogen from the gas phase by means of positron lifetime spectroscopy (PLS) and Doppler broadening spectroscopy (DBS) was carried out. In the result of penetration and accumulation of hydrogen, significant changes of annihilation characteristics occurred due to the defect structure changing. The investigated samples contained hydrogen in concentrations varying from 0 to 0.961 wt.%. Several stages of hydrogen interaction with the metal structure were revealed.

Effect of Fe2O3 Dopant on Electronic Densities and Electrical Properties of ZnO-Based Varistors

2011 ◽  
Vol 415-417 ◽  
pp. 1042-1045
Author(s):  
Wen Deng ◽  
Zhen Quan Lei ◽  
Jiao Ling Zhao ◽  
Yan Qiong Lu ◽  
Ding Kang Xiong
Keyword(s):  
Electrical Properties ◽  
Positron Lifetime ◽  
Nonlinear Coefficient ◽  
Doppler Broadening ◽  
Donor Concentration ◽  
Current Voltage ◽  
Electronic Densities ◽  
Current Voltage Characteristics ◽  
Doppler Broadening Spectra ◽  
Coincidence Doppler Broadening

The effect of the Fe2O3dopant on the electronic densities and the electrical properties has been studied in a ZnO-Bi2O3-SnO2-Co2O3-MnO2-TiO2-Ni2O3-Fe2O3system by the measurements of positron lifetime spectra, coincidence Doppler broadening spectra and current-voltage characteristics. The results show that the 3d electron signal in the spectrum of the varistor increases with the Fe2O3content. The addition of small amount of Fe2O3into the ZnO-based varistor leads to an increase in the donor concentration in the bulk and the defects in the varistor. As the Fe2O3content increased, the threshold voltage (VT) and the nonlinear coefficient (α) of the varistor decreased monotonously.

Defects Distribution of Pr2Fe14B Hard Magnetic Magnet from Amorphous to Nanostructures Characterized by Positron Annihilation Spectroscopy

2005 ◽  
Vol 475-479 ◽  
pp. 2123-2126
Author(s):  
Yu Cheng Wu ◽  
W. Sprengel ◽  
K. Reimann ◽  
K.J. Reichle ◽  
D. Goll ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Grain Growth ◽  
Melt Spinning ◽  
Positron Lifetime ◽  
Positron Annihilation Spectroscopy ◽  
Amorphous Structure ◽  
Defect Distribution ◽  
Positron Lifetime Spectroscopy ◽  
Positron Lifetimes ◽  
Shape And Size

The defect distributions have been investigated using positron lifetime spectroscopy on amorphous and nanocrystalline Pr2Fe14B samples, produced by melt-spinning and nanocrystallization route. The main two components can be concluded that were ascribed to vacancy-like defects in the intergranular layers or the interfaces, and microvoids or large free volumes with size compared to several missing atoms at the interactions of the atomic aggregates or the crystallites. The remarkable changes in the positron lifetimes from the amorphous structure to the nanocrystalline with varied sizes can be interpreted, indicating that the structural transformation and the grain growth induce the defect distribution changes occurring at the interfaces with different shape and size.

Positron Pulsing System for Variable Energy Positron Lifetime Spectroscopy

1992 ◽  
Vol 105-110 ◽  
pp. 1993-1996 ◽  
Author(s):  
Ryoichi Suzuki ◽  
Yoshinori Kobayashi ◽  
Tomohisa Mikado ◽  
Hideaki Ohgaki ◽  
M. Chiwaki ◽  
...  
Keyword(s):  
Positron Lifetime ◽  
Positron Lifetime Spectroscopy ◽  
Variable Energy

Defect analysis in FeAl and FeSi with positron lifetime spectroscopy and Doppler broadening

1999 ◽  
Vol 7 (3-4) ◽  
pp. 259-267 ◽  
Author(s):  
A. Broska ◽  
J. Wolff ◽  
M. Franz ◽  
Th. Hehenkamp
Keyword(s):  
Positron Lifetime ◽  
Doppler Broadening ◽  
Defect Analysis ◽  
Positron Lifetime Spectroscopy

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.

Proton Irradiation Induced Defects in 611- and 4H-SiC

1998 ◽  
Vol 540 ◽  
Author(s):  
Werner Puff ◽  
Adam G. Balogh ◽  
Peter Mascher
Keyword(s):  
Proton Irradiation ◽  
Positron Lifetime ◽  
Doppler Broadening ◽  
Defect Complexes ◽  
Radiation Induced ◽  
Positron Lifetime Spectroscopy ◽  
Induced Defects ◽  
Irradiation Induced Defects ◽  
Type Sample

AbstractAnnealing of defects in proton irradiated bulk n-type 6H- and semi-insulating 4H-SiC has been investigated by positron lifetime spectroscopy and Doppler-broadening measurements. For the n-type sample radiation induced defects in dependence of the proton fluence were studied. Three or four annealing stages were found, during which the formation of larger defect complexes could be observed.

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