Defect studies in crystals by means of channeling

1968 ◽  
Vol 46 (6) ◽  
pp. 653-662 ◽  
Author(s):  
E. Bøgh
Keyword(s):  
Nuclear Reactions ◽  
Depth Resolution ◽  
Atomic Layer ◽  
Orientation Dependence ◽  
Crystal Defects ◽  
Structural Defects ◽  
Experimental Conditions ◽  
Light Ions ◽  
Set Up ◽  
Fast Light

Channeling of fast, light ions (e.g. protons and α particles) in crystals containing displaced atoms is discussed on the basis of Lindhard's theory, with the particular purpose of applying channeling as a tool for studying crystal defects. Measurements of the orientation dependence of the yield of close-encounter processes, such as nuclear reactions and wide-angle elastic scattering, can provide information about the depth distribution of structural defects in the first few microns beneath the surface of a single crystal. The relation between the yield and defect concentration is derived. This relation has led to a new double-alignment technique that combines channeling and blocking, and increases considerably the sensitivity for detecting structural defects.Scattering yield measurements in tungsten and silicon crystals covered with amorphous oxide layers of accurately known thickness are used to verify the results of the theoretical discussion. Double alignment is demonstrated. Criteria for selecting the optimal experimental conditions are set up. The sensitivity of the method for detecting lattice disorder corresponds to the displacement of ~1014–1015 atoms per cm2 (i.e. less than one atomic layer); the depth resolution with which, for example, radiation damage may be determined is ~50 Å.

Application of Channeling to Defect Studies in Crystals

1980 ◽  
Vol 2 ◽  
Author(s):  
W. K. Chu
Keyword(s):  
Defect Density ◽  
Bond Distance ◽  
Crystal Defects ◽  
Structural Defects ◽  
Substitutional Impurity ◽  
Structure Information ◽  
Surface And Interface ◽  
Impurity Atoms ◽  
Light Ions ◽  
Fast Light

ABSTRACTChanneling of fast, light ions in crystals has been widely used as a tool for studying crystal defects. Backscattering yield measurement on ions incident along major axial or planar crystalline directions provides information on the depth distribution of the structural defects in the first few microns. The channeling technique in defect detection is not as sensitive as Transmission Electron Spectroscopy, nor is it accurate in measuring the absolute numbers of defect density. Channeling measurements can give only an indication of the degree of lattice disorder. It is possible to distinguish one type of defect from another by carefully studying the energy dependence of the dechanneling. The dechanneling interpretation is not always unique, and in practice it is difficult to obtain structure information through that method. Despite these negative qualities, channeling is an attractive and unique method in certain defect studies. For example, it is sensitive for studying the lattice location of impurity atoms at substitutional or interstitial sites. Clustering of substitutional impurity atoms will show a displacement of the impurity atoms from lattice sites due to the change of bond distance. Channeling is sensitive for measuring impurity displacement as small as 0.1A°. This has been demonstrated in the study of arsenic clustering formation in Si. Interfacial relaxation and contraction in a multi-layered structure made by molecular beam epitaxy has been detected by dechanneling along various axial directions. Channeling study on surface and interface structures has developed over the past few years. In this paper, I will use examples to illustrate the unique features of the channeling technique and its application to defect studies in single crystals.

Characterization of Defects and Interfaces by the Ion Channeling Technique

1984 ◽  
Vol 41 ◽  
Author(s):  
W. K. Chu ◽  
S. T. Picraux
Keyword(s):  
Ion Beam ◽  
Strain Analysis ◽  
Crystal Defects ◽  
Interfacial Structure ◽  
Heteroepitaxial Growth ◽  
Ion Channeling ◽  
Light Ions ◽  
Recent Developments ◽  
Fast Light

AbstractChanneling of fast, light ions in crystals has been widely used as a tool for studying crystal defects. This subject has been reviewed earlier at MRS-1980. During MRS-1980, principles of ion channeling, and examples of channeling analysis on bulk defects and surface structures, lattice location of impurities, and clustering phenomena were given. In this review, we give a brief overview of defect studies by the channeling technique and then elaborate on recent developments in channeling analysis of interfacial structure. The ion beam channeling technique permits characterization of heteroepitaxial growth starting at monolayer coverages and allows quantitative measurement of the lattice strain in heteroepitaxial layers. The strain analysis has been developed for multilayer structures and, for example, the tetragonal distortions of strained-layer superlattices can be determined for lattice mismatches as low as 0.2% corresponding to lattice distortions of 0.01Å.

4H-SiC Metal-Oxide-Semiconductor (MOS) Capacitors Fabricated by Oxidation in a Tungsten Lamp Furnace in Combination with a Microwave Plasma and Subsequent Deposition of Al2O3

2007 ◽  
Vol 556-557 ◽  
pp. 627-630 ◽  
Author(s):  
Svetlana Beljakowa ◽  
Thomas Frank ◽  
Gerhard Pensl ◽  
Kun Yuan Gao ◽  
Florian Speck ◽  
...  
Keyword(s):  
Microwave Plasma ◽  
Gate Dielectrics ◽  
Chemical Vapor ◽  
Atomic Layer ◽  
Oxide Semiconductor ◽  
Experimental Conditions ◽  
Al2o3 Layer ◽  
Mos Capacitors ◽  
Set Up ◽  
Tungsten Lamp

An alternative oxidation technique is developed and built up, which provides monatomic oxygen during the whole oxidation process. The set-up consists of a tungsten lamp furnace and a microwave-plasma. A number of different gases can be introduced into the oxidation quartz tube. In addition, an Al2O3-layer is deposited on a part of the oxide layers by atomic layer chemical vapor deposition (ALCVD). First oxidation runs result in encouraging low values of the density of interface states Dit and in the flatband voltage UFB. It turns out that with the present experimental conditions, the comparison of MOS capacitors fabricated with different dielectric layers favors gate dielectrics grown in O2/N2-ambient.

scholarly journals Structural defects in ZnO thin films grown by atomic layer deposition at low temperatures

2021 ◽  
Vol 27 (S1) ◽  
pp. 2660-2662
Author(s):  
David Elam ◽  
Eduardo Ortega ◽  
Andrey Chabanov ◽  
Arturo Ponce
Keyword(s):  
Thin Films ◽  
Atomic Layer Deposition ◽  
Low Temperatures ◽  
Atomic Layer ◽  
Structural Defects ◽  
Zno Thin Films ◽  
Layer Deposition

Atomic Layer Deposition of Ruthenium Films on Hydrogen terminated Silicon

2009 ◽  
Vol 1156 ◽  
Author(s):  
Sun Kyung Park ◽  
K. Roodenko ◽  
Yves J. Chabal ◽  
L. Wielunski ◽  
R. Kanjolia ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Atomic Layer ◽  
Initial Growth ◽  
Experimental Conditions ◽  
Metallic Component ◽  
Broadband Absorption ◽  
Lorentz Oscillator ◽  
Layer Deposition ◽  
Drude Term ◽  
Number Of Cycles

AbstractAtomic Layer deposition of thin Ruthenium films has been studied using a newly synthesized precursor (Cyclopentadienyl ethylruthenium dicarbonyl) and O2 as reactant gases. Under our experimental conditions, the film comprises both Ru and RuO2. The initial growth is dominated by Ru metal. As the number of cycles is increased, RuO2 appears. From infrared broadband absorption measurements, the transition from isolated, nucleated film to a continuous, conducting film (characterized by Drude absorption) can be determined. Optical simulations based on an effective-medium approach are implemented to simulate the in-situ broadband infrared absorption. A Lorentz oscillator model is developed, together with a Drude term for the metallic component, to describe optical properties of Ru/RuO2 growth.

scholarly journals Structure and Properties of TiO2/nanoTiO2 Bimodal Coatings Obtained by a Hybrid PVD/ALD Method on 316L Steel Substrate

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4369
Author(s):  
Marcin Staszuk ◽  
Daniel Pakuła ◽  
Łukasz Reimann ◽  
Anna Kloc-Ptaszna ◽  
Mirosława Pawlyta ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Electrochemical Properties ◽  
Surface Engineering ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Atomic Layer ◽  
Scanning Transmission Electron Microscope ◽  
Structural Defects ◽  
Structure And Properties ◽  
316L Steel

This paper presents the synergy of the effect of two surface engineering technologies—magnetron sputtering (MS-PVD) and atomic layer deposition (ALD) on the structure and properties of 316L steel. Recent studies indicate that PVD coatings, despite their thickness of a few micrometers, have many discontinuities and structural defects, which may lead to pitting corrosion after time. Applying an ALD layer to a PVD coating seals its structure and contributes to extending the service life of the coating. Investigations of the structure and morphology of the produced layers were carried out using a scanning electron microscope (SEM) and atomic force microscope (AFM). In addition, the structure of the coatings was investigated on the cross-section using a scanning-transmission electron microscope S/TEM. The tribological properties of the materials studied were determined by the ball-on-disc method. The corrosion resistance of the tested materials was determined by the electrochemical potentiodynamic method by recording the polarization curves of the anodes. Additional information about the electrochemical properties of the tested samples, including the quality, their tightness, and their resistivity, was obtained by electrochemical impedance spectroscopy (EIS). In addition, the main mechanisms of corrosion and tribological wear were determined by SEM observations after corrosion tests and after tribological tests. The study showed that the fabrication of hybrid layers by MS-PVD and ALD techniques allows obtaining coatings with electrochemical properties superior to those of layers fabricated by only one method.

Description of (Hyper-)Fragments in Hadron-Induced Reactions

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1887
Author(s):  
Theodoros Gaitanos
Keyword(s):  
Nuclear Reactions ◽  
Heavy Ion ◽  
Nuclear Fragmentation ◽  
Equilibrium Dynamics ◽  
Ion Collisions ◽  
Light Ions ◽  
Classical Transport ◽  
Nuclear Targets ◽  
Fragmentation Processes

In this article we review the important role of non-equilibrium dynamics in reactions induced by ions and hadron beams to understand the fragmentation processes inside hadronic media. We discuss the single-particle dynamics in specific sources such as spectators in heavy-ion collisions and residual nuclear targets in hadron-induced reactions. Particular attention is given to the dynamics of hyperons. We further discuss the question regarding the onset of local instabilities, which are relevant for the appearance of fragmentation phenomena in nuclear reactions. We apply the theoretical formalism, that is, semi-classical transport embedded with statistical methods of nuclear fragmentation, to reactions induced by light ions and hadron beams. We discuss the results of nuclear fragmentation and, in particular, examine the formation of hypernuclei. Such studies are important for obtaining a deeper understanding of the equation of state in fragmenting matter and are relevant for forthcoming experiments, such as PANDA at FAIR and J-PARC in Japan.

Antibiotic treatment of the breadcrumb sponge Halichondria panicea and subsequent recolonization v1

2021 ◽  
Author(s):  
Lara Schmittmann ◽  
Ute U Hentschel
Keyword(s):  
Antibiotic Treatment ◽  
Recovery Phase ◽  
Phase 3 ◽  
Experimental Conditions ◽  
Host Environment ◽  
Halichondria Panicea ◽  
Set Up ◽  
Bacterial Recolonization ◽  
Sponge Halichondria Panicea

This protocol generates sponges (Halichondria panicea) with a disturbed microbiome under controlled experimental conditions, in order to study bacterial recolonization dynamics. Bacteria-bacteria interactions can be analysed with this set-up within the host environment aiming at a better understanding of sponge-microbe symbiosis in vivo. It is divided into the sections 1) preparation, 2) antibiotic treatment and recovery phase, 3) recolonization with the natural microbiome and 4) sampling.

scholarly journals Are Further Cross Section Measurements Necessary for Space Radiation Protection or Ion Therapy Applications? Helium Projectiles

2020 ◽  
Vol 8 ◽  
Author(s):  
John W. Norbury ◽  
Giuseppe Battistoni ◽  
Judith Besuglow ◽  
Luca Bocchini ◽  
Daria Boscolo ◽  
...  
Keyword(s):  
Radiation Protection ◽  
Cross Section ◽  
Cross Sections ◽  
Nuclear Reactions ◽  
Production Cross ◽  
Cosmic Ray ◽  
Space Radiation ◽  
Radiation Shielding ◽  
Light Ions ◽  
Ion Therapy

The helium (4He) component of the primary particles in the galactic cosmic ray spectrum makes significant contributions to the total astronaut radiation exposure. 4He ions are also desirable for direct applications in ion therapy. They contribute smaller projectile fragmentation than carbon (12C) ions and smaller lateral beam spreading than protons. Space radiation protection and ion therapy applications need reliable nuclear reaction models and transport codes for energetic particles in matter. Neutrons and light ions (1H, 2H, 3H, 3He, and 4He) are the most important secondary particles produced in space radiation and ion therapy nuclear reactions; these particles penetrate deeply and make large contributions to dose equivalent. Since neutrons and light ions may scatter at large angles, double differential cross sections are required by transport codes that propagate radiation fields through radiation shielding and human tissue. This work will review the importance of 4He projectiles to space radiation and ion therapy, and outline the present status of neutron and light ion production cross section measurements and modeling, with recommendations for future needs.

scholarly journals Enhanced photocatalytic bacterial inactivation of atomic-layer deposited anatase-TiO2 thin films on rutile-TiO2 nanotubes

2020 ◽  
Vol 19 (3) ◽  
pp. 399-405
Author(s):  
Joel Molina-Reyes ◽  
Alejandra Romero-Morán ◽  
José L. Sánchez-Salas
Keyword(s):  
Thin Films ◽  
Photocatalytic Activity ◽  
Tio2 Nanotubes ◽  
Considerable Increase ◽  
Atomic Layer ◽  
Surface Modifications ◽  
Anatase Tio2 ◽  
Bacterial Inactivation ◽  
Tio2 Thin Films ◽  
Experimental Conditions

Experimental conditions to fabricate rutile-TiO2 nanotubes coated with a conformal anatase-TiO2 thin layer using ALD were reported. A considerable increase in the photocatalytic activity associated with these surface modifications was also observed.

Sign in / Sign up

Export Citation Format

Share Document