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1

Defect Transformations in Ion Bombarded InGaAsP

100%

Ratajczak R., Turos A., Stonert A., Nowicki L., Strupiński W.

Acta Physica Polonica A

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2011

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vol. 120

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issue 1

136-139

EN

Damage buildup and defect transformations at temperatures ranging from 15 K to 300 K in ion bombarded InGaAsP epitaxial layers on InP were studied by in situ Rutherford backscattering/channeling measurements using 1.4 MeV ^4He ions. Ion bombardment was performed using 150 keV N ions and 580 keV As ions to fluences ranging from 5 × 10^{12} to 6 × 10^{14} at./cm^2. Damage distributions were determined using the McChasy Monte Carlo simulation code assuming that they consist of randomly displaced lattice atoms and extended defects producing bending of atomic planes. Steep damage buildup up to amorphisation with increasing ion fluence was observed. Defect production rate increases with the ion mass and decreases with the implantation temperature. Parameters of damage buildup were evaluated in the frame of the multi-step damage accumulation model. Following ion bombardment at 15 K defect transformations upon warming up to 300 K have also been studied. Defect migration beginning above 100 K was revealed leading to a broad defect recovery stage with the activation energy of 0.1 eV for randomly displaced atoms and 0.15 eV for bent channels defects.

2

Channeling Study of Co and Mn Implanted and Thermally Annealed Wide Band-Gap Semiconducting Compounds

86%

Ratajczak R., Werner Z., Barlak M., Pochrybniak C., Stonert A., Zhao Q.

Acta Physica Polonica A

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2015

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vol. 128

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issue 5

845-848

EN

The defect build-up, structure recovery and lattice location of transition metals in ion bombarded and thermally annealed ZnO and GaN single crystals were studied by channeled Rutherford backscattering spectrometry and channeled particle-induced X-ray emission measurements using 1.57 MeV ⁴He ions. Ion implantation to a fluence of 1.2×10¹⁶ ions/cm² was performed using 120 keV Co and 120 keV Mn ions. Thermal annealing was performed at 800°C in argon flow. Damage distributions were determined using the Monte Carlo McChasy simulation code. The simulations of channeled Rutherford backscattering spectra reveal that the ion implantation leads to formation of two types of defect structures in ZnO and GaN such as point and extended defects, such as dislocations. The concentrations of both types of defects are at a comparable level in both structures and for both implanted ions. Differences between both implantations appear after thermal annealing where the Mn-doped ZnO reveals much better transition metals substitution and recovery effect.

3

Resonant Photoemission Spectroscopy Study on the Contribution of the Yb 4f States to the Electronic Structure of ZnO

86%

Demchenko I., Melikhov Y., Konstantynov P., Ratajczak R., Barcz A., Guziewicz E.

Acta Physica Polonica A

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2018

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vol. 133

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issue 4

907-909

EN

The electronic structure of Yb implanted ZnO has been studied by the resonant photoemission spectroscopy. The contribution of the Yb 4f partial density of states is predominant at binding energy about 7.5 and ≈11.7 eV below the VB maximum. At photon energy about 182 eV the multiplet structure around 11.7 eV shows the strongest resonance that corresponds to the ¹I multiplet which is almost exclusively responsible for this resonance, while ³H and ³F states are responsible for the resonance around 7.5 eV. It was also found that the Yb 4f partial density of states distribution shows some similarity to Yb₂O₃.

4

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

86%

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

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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.

5

On the Question of Ferromagnetism in Proton and He-Irradiated Carbon

86%

Szczytko J., Juszyński P., Teliga L., Twardowski A., Stonert A., Ratajczak R., Korman A.

Acta Physica Polonica A

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2008

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vol. 114

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issue 5

1387-1390

EN

We tried to repeat the observation of the ferromagnetic response in proton and He-irradiated carbon made by the group of Esquinazi et al. We used He^+ and H^+ beams focused on graphite sample. The amount of charge deposited in the sample was comparable to the amount of charge used by Esquinazi. Magnetic measurements were performed in SQUID magnetometer. The magnetization of the samples before and after irradiation was compared. We did not observe any ferromagnetic enhancement of magnetization of our irradiated samples. Even if experiment was not the same as Esqinazi's one, we can exclude some of the mechanisms of ferromagnetism proposed by Esquinazi.

6

Electron Microscopy and X-ray Diffraction Study of AlN Layers

86%

Kowalczyk A., Jagoda A., Mücklich A., Matz W., Pawłowska M., Ratajczak R., Turos A.

Acta Physica Polonica A

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2002

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vol. 102

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issue 2

221-225

EN

AlN nanocrystalline layers and superstructures are used in the modern optoelectronic technology as reflecting mirrors in semiconductor lasers. In the present work the properties of AlN films prepared by sputtering methods from an AlN target in reactive Ar + N plasma were investigated. The characterisation was performed with HRTEM, SEM, glancing angle XRD and RBS methods. The present measurements confirmed the polycrystalline structure of AlN layers and enabled the evaluation of their grain size. The roughness and thickness of the layers were additionally determined by ellipsometric and profilometric measurements.

7

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

73%

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.

8

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

73%

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.

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Defect Transformations in Ion Bombarded InGaAsP

Channeling Study of Co and Mn Implanted and Thermally Annealed Wide Band-Gap Semiconducting Compounds

Resonant Photoemission Spectroscopy Study on the Contribution of the Yb 4f States to the Electronic Structure of ZnO

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

On the Question of Ferromagnetism in Proton and He-Irradiated Carbon

Electron Microscopy and X-ray Diffraction Study of AlN Layers

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

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