Search results

1

Change ofα-Particle Stopping Power in Ni at the Curie Temperature

100%

Pawłowski B., Moneta M.

Acta Physica Polonica A

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2003

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vol. 103

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issue 5

433-440

EN

Experiments showing that the ion-solid state interaction characteristics change at T_C, the Curie temperature, were recapitulated. It was shown that the experimental results for the increase in theα-particles stopping power in Fe and Gd foils can be approximately described by the Bethe theory of stopping power with Stoner model for band ferromagnetism. The experimental result for increase in 5.486 MeVα-particles stopping power in 0.89 mg/cm^2 Ni foil after transition from ferro- to paramagnetic phase at T_C was presented and it was shown to be in a good correlation with the previous data and with the theoretical evaluation.

2

Electronic Energy Loss of the Partially Stripped Boron-Like and Carbon-Like Fast Ions

100%

Gümüş H., Özalp C., Köroğlu A.

Acta Physica Polonica A

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2003

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vol. 103

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issue 4

349-363

EN

An analytical formula of the electronic stopping power expression in this study was derived for swift boron-like and carbon-like ions by using first-order perturbation theory and frozen-charge-state model. The Hartree- Fock-Slater determinant was used for the description of the bound electrons attached to ions in the ground state and orbital-screening parameter was determined by variational method. The calculated ground state energies in this study were compared with the results of Clementi-Roetti and they are in good agreement with 5%. It has been observed that the difference of energy loss for boron-like and carbon-like projectiles in a frozen-charge state increases as an atomic number increases. Furthermore, the analytical expression of the effective charge of boron-like and carbon-like projectiles was derived.

3

Response of ZnO/GaN Heterostructure to Ion Irradiation

80%

Barcz A., Pągowska K., Kozubal M., Guziewicz E., Borysiewicz M., Dyczewski J., Jakieła R., Ratajczak J., Snigurenko D., Dynowska E.

Acta Physica Polonica A

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2015

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vol. 128

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issue 5

832-835

EN

In this paper we report on the analysis of Al⁺-implanted ZnO/GaN bilayers in search for the damage production mechanism and possible ion mixing. 100 nm or 200 nm thick ZnO epitaxial layers were grown on GaN substrates by either sputter deposition or atomic layer deposition technique followed by adequate annealing. Ion irradiations of ZnO/GaN were carried out at room temperature using 200 keV Al⁺ ions with fluences of 2×10¹⁵ and 10¹⁶ at./cm². Unprocessed and irradiated samples were characterized by the Rutherford backscattering spectrometry in channeling geometry (RBS\c), X-ray diffraction and transmission electron microscopy. Additionally, secondary ion mass spectrometry was employed for the aforementioned samples as well as for the implanted samples subjected to further annealing. It was found that the damage distributions in ZnO/GaN differ considerably from the corresponding defect profiles in the bulk ZnO and GaN crystals, most probably due to an additional strain originating from the lattice mismatch. Amount of intermixing appears to be relatively small; apparently, efficient recombination prevents foreign atoms to relocate to large distances.

4

RBS/Channeling and TEM Study of Damage Buildup in Ion Bombarded GaN

80%

Pągowska K., Ratajczak R., Stonert A., Turos A., Nowicki L., Sathish N., Jóźwik P., Muecklich A.

Acta Physica Polonica A

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2011

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vol. 120

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issue 1

153-155

EN

A systematic study on structural defect buildup in 320 keV Ar-ion bombarded GaN epitaxial layers has been reported, by varying ion fluences ranged from 5 × 10^{12} to 1 × 10^{17} at./cm^2. 1 μm thick GaN epitaxial layers were grown on sapphire substrates using the metal-organic vapor phase epitaxy technique. Rutherford backscattering/channeling with 1.7 MeV^4He beam was applied for analysis. As a complementary method high resolution transmission electron microscopy has been used. The later has revealed the presence of extended defects like dislocations, faulted loops and stacking faults. New version of the Monte Carlo simulation code McChasy has been developed that makes it possible to analyze such defects on the basis of the bent channel model. Damage accumulation curves for two distinct types of defects, i.e. randomly displaced atoms and extended defects (i.e. bent channel) have been determined. They were evaluated in the frame of the multistep damage accumulation model, allowing numerical parameterization of defect transformations occurring upon ion bombardment. Displaced atoms buildup is a three-step process for GaN, whereas extended defect buildup is always a two-step process.

5

Channelling of H^0 and H^+ in Si Single Crystal

80%

Moneta M., Gront K., Gwizdałła T., Czerbniak J.

Acta Physica Polonica A

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2002

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vol. 102

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issue 6

759-766

EN

The differences in the Rutherford backscattering angular spectra measured for 100 keV hydrogen atoms H^0 and protons H^+ backscattered from Si crystal are reported and analysed. It was shown that the H^0 atom beam is better channelled in the pure crystal and is much more sensitive to the crystal surface coverage, particularly Au layer than the H^+ ion beam. The deep crystal regions seem to strengthen this differences.

6

Analysis of Crystal Lattice Deformation by Ion Channeling

80%

Jóźwik P., Sathish N., Nowicki L., Jagielski J., Turos A., Kovarik L., Arey B., Shutthanandan S., Jiang W., Dyczewski J., Barcz A.

Acta Physica Polonica A

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2013

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vol. 123

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issue 5

828-830

EN

A model of dislocations has been developed for the use in Monte Carlo simulations of ion channeling spectra obtained for defected crystals. High resolution transmission electron microscopy micrographs show that the dominant type of defects in the majority of ion irradiated crystals are dislocations. The RBS/channeling spectrum is then composed of two components: one is due to direct scattering on randomly displaced atoms and the second one is related to beam defocussing on dislocations, which produce predominantly crystal lattice distortions, i.e. bent channels. In order to provide a correct analysis of backscattering spectra for the crystals containing dislocations we have modified the existing Monte Carlo simulation code "McChasy". A new version of the code has been developed by implementing dislocations on the basis of the Peierls-Nabarro model. Parameters of the model have been determined from the high resolution transmission electron microscopy data. The newly developed method has been used to study the Ar-ion bombarded SrTiO_3 samples. The best fit to the Rutherford backscattering/channeling spectra has been obtained by optimizing the linear combination of two kinds of defects: displaced atoms and bent channels. The great virtue of the Monte Carlo simulation is that unlike a traditional dechanneling analysis it allows quantitative analysis of crystals containing a mixture of different types of defects.

7

Stopping Power and Energy Straggling of Channeled He-Ions in GaN

80%

Turos A., Ratajczak R., Pągowska K., Nowicki L., Stonert A., Caban P.

Acta Physica Polonica A

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2011

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vol. 120

|

issue 1

163-166

EN

GaN epitaxial layers are usually grown on sapphire substrates. To avoid disastrous effect of the large lattice mismatch a thin polycrystalline nucleation layer is grown at 500°C followed by the deposition of thick GaN template at much higher temperature. Remnants of the nucleation layer were visualized by transmission electron microscopy as defect agglomeration at the GaN/sapphire interface and provide a very useful depth marker for the measurement of channeled ions stopping power. Random and aligned spectra of He ions incident at energies ranging from 1.7 to 3.7 MeV have been measured and evaluated using the Monte Carlo simulation code McChasy. Impact parameter dependent stopping power has been calculated for channeling direction and its parameters have been adjusted according to experimental data. For virgin, i.e. as grown, samples, the ratio of channeled to random stopping power is constant and amounts to 0.7 in the energy range studied. Defects produced by ion implantation largely influence the stopping power. For channeled ions the variety of possible trajectories leads to different energy loss at a given depth, thus resulting in much larger energy straggling than that for the random path. Beam energy distributions at different depths have been calculated using the McChasy code. They are significantly broader than those predicted by the Bohr formula for random direction.

8

Focused Ion Beam Imaging of Defects in Multicrystalline Si for Photovoltaic Application

80%

Miyamura Y., Sekiguchi T., Chen J., Li J., Watanabe K., Kumagai K., Ogura A.

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vol. 125

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issue 4

991-993

EN

We demonstrate the imaging of the extended defects in Si materials using a focused ion beam instrument. Since Ga-ion beam has small penetration depth and high channeling character compared with electron beam, the secondary electron signal of focused ion beam is more sensitive to the surface morphology and crystallinity. We have tried to use this secondary electron imaging of focused ion beam for observation of various extended defects in Si materials for photovoltaic and semiconductor devices. As for the texture of multicrystalline Si, some grains are imaged darker than the others. It suggests that the crystal orientation gives different channeling effect on the primary Ga-ion beam, resulting in the different secondary electron yield. The grain boundaries and lineage in multicrystalline Si are shown as bright lines and patterns in the image. Although it may reflect the surface morphologies, these contrasts may be attributed to the channeling contrast due to lattice displacement or distortion. The contrast mechanism of FIB imaging is discussed.

9

RBS/Channeling Analysis of Zinc Oxide Films Grown at Low Temperature by Atomic Layer Deposition

61%

Ratajczak R., Stonert A., Guziewicz E., Gierałtowska S., Krajewski T., Luka G., Wachnicki L., Witkowski B., Godlewski M.

Acta Physica Polonica A

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2013

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vol. 123

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issue 5

899-903

EN

The results of the Rutherford backscattering/channeling study of ZnO layers are presented. ZnO layers were deposited on the silicon single crystals and GaN epitaxial layers at low temperature by atomic layer deposition. Deposition temperature varied between 100 and 300°C. A random spectra analysis was performed to determine layer thickness and composition. In turn, analysis of the aligned spectra allows us to study evolution of ingrown defects. The Rutherford backscattering study supports the results of X-ray photoelectron spectroscopy measurements, performed separately, that the ZnO-ALD layers deposited at low temperature contain a higher oxygen content. Composition measurements, performed as a function of growth temperature, show that oxygen content decreases with the increasing temperature of the atomic layer deposition growth process.

10

Damage Accumulation in Nuclear Ceramics

61%

Thomé L., Moll S., Jagielski J., Debelle A., Garrido F., Sattonnay G.

Acta Physica Polonica A

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2011

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vol. 120

|

issue 1

7-12

EN

Ceramics are key engineering materials in many industrial domains. The evaluation of radiation damage in ceramics placed in a radiative environment is a challenging problem for electronic, space and nuclear industries. Ion beams delivered by various types of accelerators are very efficient tools to simulate the interactions involved during the slowing-down of energetic particles. This article presents a review of the radiation effects occurring in nuclear ceramics, with an emphasis on new results concerning the damage build-up. Ions with energies in the keV-GeV range are considered for this study in order to explore both regimes of nuclear collisions (at low energy) and electronic excitations (at high energy). The recovery, by electronic excitation, of the damage created by ballistic collisions (swift heavy ion beam induced epitaxial recrystallization process) is also reported.

Refine search results

Change ofα-Particle Stopping Power in Ni at the Curie Temperature

Electronic Energy Loss of the Partially Stripped Boron-Like and Carbon-Like Fast Ions

Response of ZnO/GaN Heterostructure to Ion Irradiation

RBS/Channeling and TEM Study of Damage Buildup in Ion Bombarded GaN

Channelling of H^0 and H^+ in Si Single Crystal

Analysis of Crystal Lattice Deformation by Ion Channeling

Stopping Power and Energy Straggling of Channeled He-Ions in GaN

Focused Ion Beam Imaging of Defects in Multicrystalline Si for Photovoltaic Application

RBS/Channeling Analysis of Zinc Oxide Films Grown at Low Temperature by Atomic Layer Deposition

Damage Accumulation in Nuclear Ceramics