• Applied Science and Convergence Technology
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• v.25 no.5
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• pp.85-87
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• 2016

Coincidence Doppler broadening and positron lifetime methods in positron annihilation spectroscopy has been used to analyze defect structures in metal, semiconductor and polycrystal, respectively. The S parameter and the lifetime (${\tau}$) value show that the defects were strongly related with vacancies. A positive relationship existed between the scanning electron microscope (SEM) images and the positron annihilation spectroscopy (PAS). According to the SEM images and PAS results, measurements of the defects with PAS indicate that it was more affected by the defect than the purity.

• Journal of the Korean Physical Society
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• v.73 no.12
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• pp.1895-1898
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• 2018

The mechanical properties of Al, Ti, Fe, and Cu metals p-type Si, and n-type Si were investigated by using coincidence Doppler broadening (CDB) positron annihilation spectroscopy. The samples in this experiment were irradiated by using X-rays at generating powers for up to 9 kW. The data taken after the irradiation showed all the characteristic features predicted from defects with vacancies. The S parameter values of the metals were generally less than those of semiconductors such as p-type Si and n-type Si. The relationship between n-type Si and p-type Si were more affected when n-type Si rather than p-type Si was irradiated with X-rays.

• Journal of the Korean Vacuum Society
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• v.20 no.5
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• pp.367-373
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• 2011

It is described that the proton beam induces micro defects and electronic deep levels in Cz single crystal silicon. Enhance signal-to-noise ratio, Coincidence Doppler Broadening Positron Annihilation Spectroscopy has been applied to study of characteristics of p type and n type silicon samples. In this investigation the numerical analysis of the Doppler spectra was employed to the determination of the shape parameter, S, defined as the ratio between the amount of counts in a central portion of the spectrum and the total counts of whole spectrum. The samples were exposed by 4.0 MeV proton beams ranging from 0 to ${\sim}10^{14}$ ptls. The S-parameter values were increased as increasing the irradiated proton beam, that indicated the defects generate more.

• Korean Journal of Materials Research
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• v.16 no.7
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• pp.455-459
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• 2006

Coincidence Doppler Broadening (CDB) of positron annihilation spectroscopy was applied to analyze defects in the chemical state of Department of Physics, $Gd_2O_2S$:Tb intensifying screens. The screen samples were irradiated by 80 MV X-rays in hospital and were used for 0, 2, 4, and 6 years respectively. There was a positive relationship between the S-parameter values and time of exposure to X-rays. Most of the defects were indicated to have been generated by X-rays. A 1D CDB was developed in order to reduce the background noise, and the S-parameter values of the $Gd_2O_2S$:Tb intensifying screens, using the 1D CDB, varied between 0.4974 and 0.4991.

• Journal of the Korean Vacuum Society
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• v.21 no.5
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• pp.225-232
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• 2012

It is described that the proton beam induceds micro-size defects and electronic deep levels in n or p type single crystal silicon. Positron lifetime and Coincidence Doppler Broadening Positron Annihilation Spectroscopy were applied to study of characteristics of p type and n type silicon samples. In this investigation the numerical analysis of the Doppler spectra was employed to the determination of the shape parameter, S, defined as the ratio between the amount of counts in a central portion of the spectrum and the total counts of whole spectrum. The samples were exposed by 3.98 MeV proton beams ranging between 0 to ${\sim}10^{14}$ particles. The S-parameter values strongly depend on the irradiated proton beam, that indicated the defects generate more. Positron lifetime shows that positrons trapped in vacancies and lifetime ${\tau}_2$ increased according to proton irradiation.

• Korean Journal of Materials Research
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• v.18 no.8
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• pp.427-431
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• 2008

The mechanical property of a phosphore layer was investigated by measuring the resolution (LP/mm) and by positron annihilation spectroscopy and SEM. Image plate samples containing the phosphore layer were irradiated by X-rays in a hospital numerous times over a course of several years. The LP/mm values of a (Ba,Sr)FBr : Eu image plate irradiated by X-rays varied between 2.2 and 2.0 over a period of four years. Coincidence Doppler Broadening (CDB) positron annihilation spectroscopy was used to analyze defect structures. The S parameters of the samples from hospital use varied from 0.6219 to 0.6232. There was a positive relationship between the time of exposure to the X-rays and the S parameters. Most of the defects were found to have been generated by X-rays.

• Journal of the Korean Vacuum Society
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• v.18 no.6
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• pp.447-452
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• 2009

Enhance signal-to-noise ratio, Coincidence Doppler Broadening positron method has been applied to study of characteristics of BaSrFBr:Eu film sample. In this investigation the numerical analysis of the Doppler spectra was employed to the determination of the shape parameter, S, defined as the ratio between the amount of counts in a central portion of the spectrum and the total counts of whole spectrum. The films were exposed by 0, 3, 5, and 7.5 MeV proton beams ranging from 0 to $10^{13}$ ptls. The S-parameter values were increased as increasing the exposed time and the energies, that indicated the defects generate more.

• Journal of the Korean Vacuum Society
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• v.19 no.6
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• pp.489-494
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• 2010

Enhance signal-to-noise ratio, slow positron coincidence Doppler Broadening method has been applied to study of characteristics of $Nb_3Ge$ superconductor film, which were performed from 20 K to 300 K sample temperature near Tc of it. In this investigation the numerical analysis of the Doppler spectra was employed to the determination of the shape parameter, S, defined as the ratio between the amount of counts in a central portion of the spectrum and the total counts of whole spectrum. The S-parameter values between 0.598 and 0.594 were decreased while the temperature were decreasing, that indicated the voids into the samples. The temperature dependence came from specific positron trapping rate into the vacancy-type defects. It is believed that the positrons annihilate with normal-electrons instead of super-electrons in the Nb3Ge superconductor.

• Journal of the Korean Vacuum Society
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• v.22 no.5
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• pp.250-256
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• 2013

It is described that the proton beam induces micro-size defects and electronic deep levels in luminescence Thin Film. Coincidence Doppler Broadening Positron Annihilation Spectroscopy (CDBPAS) and Positron lifetime Spectroscopy were applied to study of characteristics of a poly crystal samples. In this investigation the numerical analysis of the Doppler spectra was employed to the determination of the shape parameter, S-parameter value. The samples were exposed by 3.0 MeV proton beams with the intensities ranging between 0 to ${\sim}10^{14}$ particles. The S-parameter values decreased as increased the proton beam, that indicates the protons trapped in vacancies. Lifetime ${\tau}_1$ shows that positrons are trapped in mono vacancies. Lifetime ${\tau}_2$ is not changed according to proton irradiation that indicate the cluster vacancies of the grain structure.

• Journal of the Korean Vacuum Society
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• v.17 no.2
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• pp.160-164
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• 2008

The Characterization of $MgB_2$ Thin Film by Slow Positron Annihilation Spectroscopy Enhance signal-to-noise ratio, slow positron coincidence Doppler Broadening method has been applied to study of characteristics of $MgB_2$ superconductor film, which were performed at 30 K and 50 K sample temperature near Tc of it. In this investigation the numerical analysis of the Doppler spectra was employed to the determination of the shape parameter, S, defined as the ratio between the amount of counts in a central portion of the spectrum and the total counts of whole spectrum. The S-parameter values were increased then decreased while the positron implantation energies were increasing, that indicated the diffusion into the samples. The S-parameters of the anisotropic 1 ${\mu}m$ $MgB_2$ thin film which were implanted by positrons at 10 keV are 0.567 at 30 K and 0.570 at 50 K. It is believed that the positrons annihilate with normal-electrons instead of super-electrons in the $MgB_2$ superconductor.