Slow positron annihilation studies of vacancy-type defects in the near-surface region of Cu and Nb before and after wear

1999 ◽  
Vol 68 (3) ◽  
pp. 325-327
Author(s):  
H.D. Gu ◽  
T.M. Wang ◽  
W.J. Wang ◽  
K.M. Leung ◽  
C.Y. Chung
Keyword(s):  
Positron Annihilation ◽  
Surface Region ◽  
Near Surface ◽  
Slow Positron ◽  
Before And After

scholarly journals On the Limitations of Positron Annihilation Spectroscopy in the Investigation of Ion-Implanted FeCr Samples

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1689
Author(s):  
Vladimir Slugen ◽  
Jarmila Degmova ◽  
Stanislav Sojak ◽  
Martin Petriska ◽  
Pavol Noga ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Positron Annihilation ◽  
Neutron Irradiation ◽  
Surface Region ◽  
Positron Beam ◽  
Positron Annihilation Spectroscopy ◽  
Radiation Embrittlement ◽  
Nuclear Facilities ◽  
Near Surface ◽  
Slow Positron

New materials for advanced fission/fusion nuclear facilities must inevitably demonstrate resistance to radiation embrittlement. Thermal and radiation ageing accompanied by stress corrosion cracking are dominant effects that limit the operational condition and safe lifetime of the newest nuclear facilities. To study these phenomena and improve the current understanding of various aspects of radiation embrittlement, ion bombardment experiments are widely used as a surrogate for neutron irradiation. While avoiding the induced activity, typical for neutron-irradiated samples, is a clear benefit of the ion implantation, the shallow near-surface region of the modified materials may be a complication to the post-irradiation examination (PIE). However, microstructural defects induced by ion implantation can be effectively investigated using various spectroscopic techniques, including slow-positron beam spectroscopy. This method, typically represented by techniques of positron annihilation lifetime spectroscopy and Doppler broadening spectroscopy, enables a unique depth-profile characterisation of the near-surface region affected by ion bombardment or corrosion degradation. One of the best slow-positron beam facilities is available at the pulsed low-energy positron system (PLEPS), operated at FRM-II reactor in Munich (Germany). Bulk studies (such as high energy ion implantation or neutron irradiation experiments) can be, on the other hand, effectively performed using radioisotope positron sources. In this paper, we outline some basics of the two approaches and provide some recommendations to improve the validity of the positron annihilation spectroscopy (PAS) data obtained on ion-irradiated samples using a conventional 22Na positron source.

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.

The Effects of Kcn Etching on Cu-Rich Epitaxial CuInSe2 Thin Films

1996 ◽  
Vol 426 ◽  
Author(s):  
P. Fons ◽  
S. Nikl ◽  
A. Yamada ◽  
M. Nishitanp ◽  
T. Wada ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Region ◽  
Etching Time ◽  
Cation Sublattice ◽  
Epitaxial Thin Films ◽  
Near Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Integrated Intensity

AbstractA series of Cu-rich CuInSe2 epitaxial thin films were grown by molecular beam epitaxy on GaAs(001) substrates from elemental sources at a growth temperature of 450 °C. All samples were grown with an excess of Cu. Electron microprobe analysis (EPMA) indicated a Cu/ In ratio of about 2.1–2.6 in the as-grown films. Additionally, the Se/ (In+Cu) ratio was observed to be ∼0.95 indicating that the films were slightly Se poor. These Cu-rich samples were etched in a KCN solution for periods ranging from 30 seconds to 3 minutes. EPMA measurements indicated that the bulk Cu/ In ratio was reduced to ∼0.92 in all films regardless of etching time. Atomic force microscopy (AFM) was used to characterize the topology of each sample before and after etching. These measurements indicated that the precipitates present on the as-grown films were removed and large nearly isotropic holes were etched into the sample to a depth of over 1000 Å even for etching times as short as 30 seconds. The samples were also evaluated both before and after etching using a Phillips MRD diffractometer with parallel beam optics and a 18,000 watt Cu rotating anode X-ray source in the chalcopyrite [001], [101], and [112] directions. A peak was observed at ∼15 degrees in the [001] scan after etching consistant with the presence of the ordered vacancy compound, CuIn3Se5. Additionally the integrated intensity ratios of the chalcopyrite (202) reflection to the chalcopyrite (101) reflection ∝(fCu-fIn)2 along the [101] direction indicated the presence of a near-surface region containing cation sublattice disorder that was subsequently removed by the etching process.

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...

GaAs(100) Surface Modifications at Elevated Temperatures, Studied By In-Situ Spectroscopic Ellipsometry

1990 ◽  
Vol 202 ◽  
Author(s):  
Huade Yao ◽  
Paul G Snyder ◽  
John A Woollam
Keyword(s):  
Spectroscopic Ellipsometry ◽  
Room Temperature ◽  
Molecular Beam ◽  
Elevated Temperatures ◽  
Surface Region ◽  
Gaas Surface ◽  
Near Surface ◽  
Before And After ◽  
Surface Changes

ABSTRACTSpectroscopic ellipsometric (SE) measurements of GaAs (100) were carried out in an ultrahigh vacuum (UHV) chamber, without arsenic overpressure, at temperatures ranging from room temperature (RT) to ∼610°C. Surface changes induced at elevated temperatures were monitored by in-situ spectroscopic ellipsometry. The SE data clearly displayed in real time the process of desorption of the GaAs-surface-oxide overlayer at ∼580°C. In addition, changes in the near-surface region were observed before and after the oxide desorption. The near-subsurface region (top 50–100 Å) became less optically dense after being heated to 540°C or higher. For comparison, a pre-arsenic-capped molecular-beam-epitaxy (MBE)-grown GaAs surface was also studied. After the arsenic cap was evaporated off at ∼350°C, this surface remained smooth and clean as it was heated to higher temperatures.

Gettering of Cu at Buried Damage Layers Made by Si Self Implantation

1989 ◽  
Vol 157 ◽  
Author(s):  
J.R. Liefting ◽  
R.J. Schreutelkamp ◽  
W.X. Lu ◽  
F.W. Saris
Keyword(s):  
Surface Layer ◽  
Thermal Annealing ◽  
Rutherford Backscattering Spectrometry ◽  
Surface Region ◽  
Amorphous Layer ◽  
High Concentration ◽  
Near Surface ◽  
Before And After ◽  
Dose Ranging ◽  
P Type

ABSTRACTChanneled implants have been performed with lOOkeV 28Si+ into p-type Si(100) to obtain a buried amorphous layer. Before and after recrystallization of the a-Si layer, Cu was implanted at an energy of 15 keV and a dose ranging from 5E13 to 1E15 I cm2- to obtain a high concentration of Cu in the near surface region. Also, Cu implants were performed into virgin Si for comparison. After Cu implantation, thermal annealing was performed at temperatures between 490 °C and 900 °C for 10 min. to 320 min. Cu profiles before and after annealing were studied with Rutherford Backscattering Spectrometry and channeling analysis. For the case where Cu was implanted after recrystallization of the buried amorphous layer, Cu was gettered at the position where the ale interfaces met during recrystallization. For the case where Cu was implanted before recrystallization, Cu diffused towards the buried a-Si region upon annealing and was trapped inside the recrystallizing buried amorphous layer. The results show that buried damage layers can effectively getter Cufrom the Si surface layer and gettering is most efficient at 600 °C.

Preparation of cross-sectional samples for near-surface TEM studies

1987 ◽  
Vol 45 ◽  
pp. 380-381
Author(s):  
R.C. Dickenson ◽  
K.R. Lawless
Keyword(s):  
Standard Sample ◽  
Surface Region ◽  
Specimen Preparation ◽  
Thick Sheet ◽  
Drill Bit ◽  
Sample Holder ◽  
Metal Interface ◽  
Cross Sectional ◽  
Near Surface ◽  
Cold Worked

In thermal oxidation studies, the structure of the oxide-metal interface and the near-surface region is of great importance. A technique has been developed for constructing cross-sectional samples of oxidized aluminum alloys, which reveal these regions. The specimen preparation procedure is as follows: An ultra-sonic drill is used to cut a 3mm diameter disc from a 1.0mm thick sheet of the material. The disc is mounted on a brass block with low-melting wax, and a 1.0mm hole is drilled in the disc using a #60 drill bit. The drill is positioned so that the edge of the hole is tangent to the center of the disc (Fig. 1) . The disc is removed from the mount and cleaned with acetone to remove any traces of wax. To remove the cold-worked layer from the surface of the hole, the disc is placed in a standard sample holder for a Tenupol electropolisher so that the hole is in the center of the area to be polished.

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