Search results

1

Image Depth Profiling AES

100%

Sekine T., Sato T.

Acta Physica Polonica A

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1992

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vol. 81

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issue 1

145-157

EN

Image depth profiling AES incorporating an image processing technique has been developed. This method reconstructs a cross-sectional image from acquired 2-dimensional and/or 3-dimensional data. A binary image produced from a secondary electron image through image processing can be used to cut the area of interest for selected area analysis. In a failure analysis of a relay contact, we found by cross-sectional image observation that Fe and Ni permeate from pin holes in an Au layer covering a Fe-Ni alloy. A VTR head made of a polycrystalline ferrite core covered with a Sendust (Si-Al-Fe alloy) layer at the gap has been analyzed. Depth distributions of Al, 0, and Fe on different grains, and Al and O distributions near grain boundaries have been successfully reassembled from the 3-dimensional data.

2

Photoinduced Defects Creation on Sulfur Passivated Surface of GaAs

63%

Żytkiewicz Z., Dobaczewski L., Gomez D., Briones F.

Acta Physica Polonica A

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1997

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vol. 92

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issue 5

1083-1086

EN

We report on photoinduced defect creation on the sulfurized (100) GaAs surface. The process manifests itself by unrecoverable temporal decrease in the photoluminescence intensity of the GaAs surface treated by (NH_{4})_{2}S_{x} solution. The results are discussed in terms of a photoinduced process of the As_{Ga} antisite generation on the sulfurized surface of GaAs.

3

Some Problems in Quantitative Auger Analysis of Metallic Alloys

63%

Mróz S., Doliński W.

Acta Physica Polonica A

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1992

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vol. 81

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issue 2

201-210

EN

Factors determining the Auger signal intensity are discussed. It is indicated that using standards is the only reasonable way for quantitative Auger analysis (QAA). Approaches to QAA without and with matrix corrections are presented. It is shown that the matrix correction connected with atomic concentrations of pure standards is the most important and that the other matrix corrections (e.g. those connected with the attenuation length and backscattering factor) do not improve appreciably the QAA exactness in many examples taken from the literature. The examples indicate that in the case of metallic alloys the properly performed QAA gives the relative atomic concentrations with the error not exceeding few percent.

4

SEM Characterization of Multilayer Structures

63%

Aristov V., Dryomova N., Kireev V., Razgonov I., Yakimov E.

Acta Physica Polonica A

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1993

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vol. 83

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issue 1

81-86

EN

The possibilities of non-destructive multilayer structure characterization using the backscattering electron and modulated cathodoluminescence modes of the SEM have been discussed. It is shown that these techniques allow one to measure the parameters of thin layers of the thickness of about 10 nm.

5

Carbon Monolith Surface Chemistry Influence on the Silver Deposit Amount and Crystallite Size

51%

Vukčević M., Kalijadis A., Jovanović Z., Laušević Z., Laušević M.

Acta Physica Polonica A

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2011

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vol. 120

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issue 2

284-288

EN

The surface of carbon monolith (CM) was chemically treated in order to obtain antibacterial filters with silver deposit for water treatment. The chemical treatment involved submerging the as-received CM in HNO_{3}, KOH and H_{2}O_{2} solution. The specific surface area was examined by N_{2} adsorption. Silver deposition at the surface of CM samples was performed using cheap and simple procedure of immersing CM samples in aqueous solution of AgNO_{3}. Temperature programmed desorption method has been used in order to investigate the nature and thermal stability of surface oxygen groups before and after silver deposition. The composition and crystalinity of silver deposits have been examined by X-ray diffraction. Chemical treatment does not cause any drastic changes of CM specific surface area, but increases a total amount of surface oxides. Amount of deposited silver is several times higher for all chemically treated samples. The results show that increasing the amount of CO yielding groups on CM surface leads to increased amount of Ag deposit and decreases its crystallite sizes

6

Electronic Energies of Interaction of Point Defects with Interfaces and Grain Boundaries

51%

Vasseur J., Deymier P., Akjouj A., Dobrzynski L., Djafari-Rouhani B.

Acta Physica Polonica A

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1992

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vol. 81

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issue 1

39-46

EN

The electronic energies of interaction of a point defect with interfaces and grain boundaries are calculated, as a function of the distance x_{03} between the point defect and the corresponding planar defect. These interaction energies are shown to have the same type of oscillations as the corresponding local electronic densities. Therefore the electronic interactions more significantly affect the energy of segregation of point defects towards interfaces when x_{03} is in the near vicinity of these interfaces, while at large distances the contribution of elastic interactions can dominate.

7

Response of ZnO/GaN Heterostructure to Ion Irradiation

51%

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.

8

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

51%

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.

9

Surface Segregation of CoPt Polycrystalline Alloy

51%

Godowski P., Ohgi T., Fujita D.

Acta Physica Polonica A

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2003

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vol. 104

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issue 1

35-44

EN

Composition-depth profiling using different emission angles of X-ray photoelectron spectroscopy showed surface enhancement of platinum concentration of the CoPt(30at%) alloy extensively annealed to 1000~K in ultrahigh vacuum. The results are compared with theoretical predictions basing on models with no crystal face dependence.

10

Calculation of Free Volume in Computer Generated Grain Boundaries

51%

Van Petegem S., Kuriplach J.

Acta Physica Polonica A

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2005

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vol. 107

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issue 5

769-775

EN

We investigate the positron lifetime distribution in grain boundaries originating from computer generated nanocrystalline configurations. We give a brief overview of the computational methods and we discuss the influence of thermal vibrations and grain size on the obtained positron lifetime distributions.

11

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

51%

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.

12

Composition of a Clean and Sulphur Covered CuNi(100) Single Crystal Surface

51%

Godowski P. J., Marcus P.

Acta Physica Polonica A

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1995

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vol. 87

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issue 3

619-630

EN

Surface composition of the CuNi(100) single crystal in the temperature range of 893÷1073 K (620÷800°C) has been investigated using low energy electron diffraction and Auger electron spectroscopy methods. A clean sample surface at moderate temperatures reveals small surface copper enrichment, with respect to the bulk Cu-rich composition. For example, at 1006 K (733°C) the copper surface concentration C^{s}_{Cu}, was determined from the quantitative Auger electron spectroscopy analysis as 0.91. After prolonged heating at higher temperatures, the copper surface concentration converges to the bulk value, i.e. at 1073 K (800°C), C^{s}_{Cu} = C^{b}_{Cu} = 0.87. Surface segregation of sulphur proceeds from (1 × 1) through p(2 × 2)S/CuNi(100) to c(2 × 2)S/CuNi(100) structures of low energy electron diffraction. In the presence of segregated sulphur the surface concentration of copper is lower.

13

Applications of Scanning Tunneling Microscopy To Solid State Physics

51%

van Kempen H., Boon E., van der Wielen M., Wildöer J., Prins M., Jansen R., Schad R.

Acta Physica Polonica A

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1998

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vol. 93

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issue 2

323-331

EN

Due to the dependence of the tunnel current to material properties like work function, density of states, and spin polarization the scanning tunneling microscope can be used to study a number of solid state physics problems. This will be illustrated with some examples. The presented examples have in common that also the role of the tip properties have to be taken explicitly into account.

14

Investigations of Au Segregation in AuNi Alloys by the Line Shape Analysis of Photoelectron Spectra

51%

Lesiak B., Biliński A., Jóźwik} A.

Acta Physica Polonica A

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2006

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vol. 109

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issue 6

701-714

EN

The surface segregation of Au in Au5Ni95 polycrystalline alloy is studied applying the line shape analysis, known as the fuzzy k-nearest neighbour rule, to the selected X-ray photoelectron and X-ray induced Auger spectra. Each line, characterised by the kinetic electron energy exhibited in the particular transition, samples the depth described by the mean escape depth depending on the inelastic mean free path of electron in the investigated material and the geometry of the measurement. The following electron transitions in the electron kinetic energy range 216.6-1486.6 eV are analysed: Au N_5N_{67}V, Ni 2p, Ni L_2M_{23}M_{45}-Ni L_3M_{45}M_{45}, Au 4d, Au 4f and the valence band transitions (overlapping Au 5d6s and Ni 3d4s transitions). The results of the quantitative analysis using the fuzzy k-nearest neighbour rule are compared to the results of quantitative analysis by the multiline approach which applies the Au 4f and Ni 2p photoelectron transitions. Both methods demonstrate Au surface segregation starting at the temperature above 200ºC. The line shape analysis was shown to be applicable for quantification of the surface region with possibility of investigating the in-depth non-uniform concentration profiles.

15

Optical Properties and Microstructure of InGaN Grown by Molecular Beam Epitaxy

45%

Böttcher T., Einfeldt S., Figge S., Kirchner V., Hommel D., Selke H., Ryder P., Bertram F., Riemann T., Christen J., Lunz U., Becker C.

Acta Physica Polonica A

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1998

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vol. 94

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issue 2

260-264

EN

The luminescence of In_{x}Ga_{1-x}N is studied for thick epitaxial layers and quantum wells. Using spatially resolved cathodoluminescence spectroscopy the commonly observed broad integral photoluminescence spectra were found to result from spectral and lateral inhomogeneous emission across the samples. Moreover, the integral photoluminescence and absorption spectra show different temperature dependences. The effects can be explained assuming fluctuations of the composition associated with a variation of the band gap.

16

Antisite Defects in Epitaxial Films of Lutetium Doped Yttrium Iron Garnets Studied by Nuclear Magnetic Resonance

45%

Chlan V., Štěpánková H., Englich J., Řezníček R., Kouřil K., Kučera M., Nitsch K.

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issue 5

846-847

EN

Series of lutetium doped yttrium iron garnet films is studied by means of ^{57}Fe nuclear magnetic resonance. Satellite spectral lines are resolved and identified in the spectra and concentrations of lutetium in dodecahedral sites as well as yttrium/lutetium antisite defects in octahedral sites are estimated. Compared to yttrium, lutetium cations are found to have stronger disposition towards creating the antisite defects.

17

Distribution of Pb^{2+} Ions in PbF_{2}-Doped CaF_{2} Crystals

45%

Paraschiva M., Nicoara I., Stef M., Bunoiu O.

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issue 3

466-470

EN

Calcium fluoride crystals doped with various concentrations of PbF_{2} have been grown using the Bridgman technique. The optical absorption spectra reveal the characteristic UV absorption bands of the Pb^{2+} ions. The distribution of the Pb^{2+}-ions along four crystals has been investigated using the optical absorption method. Taking into account the relationship between the optical absorption coefficient and the concentration of the impurities in the samples, the effective segregation coefficient of the Pb^{2+} ions has been calculated. Our study shows that the effective segregation coefficient of the Pb^{2+} ions in CaF_{2} host depends on the dopant concentration, and varies between 0.85 and 1.15, for 0.5 mol%PbF_{2} and 3 mol%PbF_{2}-doped CaF_{2}, respectively.

18

Interface Engineering in Heteroepitaxy

45%

Hong S., Chen Y., Ko H., Yao T.

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issue 4-5

541-554

EN

We report the importance of interface engineering in heteroepitaxy with examples of plasma-assisted molecular beam epitaxial ZnO growths on (0001) sapphire substrates and on (0001) GaN/sapphire templates, whose interfaces are engineered to improve and to control properties of ZnO films. The growth of rocksalt structure MgO buffer on Al_2O_3 (0001) is developed for ZnO epitaxy. By employing the MgO buffer layer, the formation of 30^o rotated mixed domains is prohibited and two-dimensional layer-by-layer growth of ZnO on sapphire substrate is achieved. High-resolution X-ray diffraction reveals the superior improvement in a crystal quality of ZnO films with an MgO buffer. Polarity of wurtzite structure ZnO films on Ga-polar GaN/sapphire templates is controlled by changing interface structures. By forming a single crystalline, monoclinic Ga_2O_3 interfacial layer between GaN and ZnO through O-plasma pre-exposure on the Ga-polar GaN surface, O-polar ZnO films are grown. By forming the ZnO/GaN heterointerface without an interfacial layer through the Zn pre-exposure on the Ga-polar GaN surface, Zn-polar ZnO films are grown.

Refine search results

Image Depth Profiling AES

Photoinduced Defects Creation on Sulfur Passivated Surface of GaAs

Some Problems in Quantitative Auger Analysis of Metallic Alloys

SEM Characterization of Multilayer Structures

Carbon Monolith Surface Chemistry Influence on the Silver Deposit Amount and Crystallite Size

Electronic Energies of Interaction of Point Defects with Interfaces and Grain Boundaries

Response of ZnO/GaN Heterostructure to Ion Irradiation

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

Surface Segregation of CoPt Polycrystalline Alloy

Calculation of Free Volume in Computer Generated Grain Boundaries

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

Composition of a Clean and Sulphur Covered CuNi(100) Single Crystal Surface

Applications of Scanning Tunneling Microscopy To Solid State Physics

Investigations of Au Segregation in AuNi Alloys by the Line Shape Analysis of Photoelectron Spectra

Optical Properties and Microstructure of InGaN Grown by Molecular Beam Epitaxy

Antisite Defects in Epitaxial Films of Lutetium Doped Yttrium Iron Garnets Studied by Nuclear Magnetic Resonance

Distribution of Pb^{2+} Ions in PbF_{2}-Doped CaF_{2} Crystals

Interface Engineering in Heteroepitaxy