scholarly journals Strain-induced structural defects and their effects on the electrochemical performances of silicon core/germanium shell nanowire heterostructures

Nanoscale ◽  
2017 ◽  
Vol 9 (3) ◽  
pp. 1213-1220 ◽  
Author(s):  
Yung-Chen Lin ◽  
Dongheun Kim ◽  
Zhen Li ◽  
Binh-Minh Nguyen ◽  
Nan Li ◽  
...  
Keyword(s):  
Structural Defects ◽  
Electrochemical Performances ◽  
Nanowire Heterostructures

Transmission electron microscopy of composite materials

1988 ◽  
Vol 46 ◽  
pp. 1012-1015
Author(s):  
K.P.D. Lagerlof
Keyword(s):  
Composite Materials ◽  
Physical Properties ◽  
Structural Defects ◽  
Structural Composites ◽  
Multiphase Materials ◽  
Structural Reinforcement ◽  
Transmission Electron ◽  
Reinforced Fiber ◽  
Particulate Reinforced Composites ◽  
Definition Of

Although most materials contain more than one phase, and thus are multiphase materials, the definition of composite materials is commonly used to describe those materials containing more than one phase deliberately added to obtain certain desired physical properties. Composite materials are often classified according to their application, i.e. structural composites and electronic composites, but may also be classified according to the type of compounds making up the composite, i.e. metal/ceramic, ceramic/ceramie and metal/semiconductor composites. For structural composites it is also common to refer to the type of structural reinforcement; whisker-reinforced, fiber-reinforced, or particulate reinforced composites [1-4].For all types of composite materials, it is of fundamental importance to understand the relationship between the microstructure and the observed physical properties, and it is therefore vital to properly characterize the microstructure. The interfaces separating the different phases comprising the composite are of particular interest to understand. In structural composites the interface is often the weakest part, where fracture will nucleate, and in electronic composites structural defects at or near the interface will affect the critical electronic properties.

High-angle electron scattering from amorphous silicon

1995 ◽  
Vol 53 ◽  
pp. 162-163
Author(s):  
M. Libera ◽  
J.A. Ott ◽  
K. Siangchaew ◽  
L. Tsung
Keyword(s):  
Electron Scattering ◽  
Amorphous Material ◽  
Structural Defects ◽  
Constant Thickness ◽  
High Angle ◽  
Fast Electrons ◽  
Angle Scattering ◽  
Stem Image ◽  
Amorphous Si ◽  
Thermal Vibrations

Channeling occurs when fast electrons follow atomic strings in a crystal where there is a minimum in the potential energy (1). Channeling has a strong effect on high-angle scattering. Deviations in atomic position along a channel due to structural defects or thermal vibrations increase the probability of scattering (2-5). Since there are no extended channels in an amorphous material the question arises: for a given material with constant thickness, will the high-angle scattering be higher from a crystal or a glass?Figure la shows a HAADF STEM image collected using a Philips CM20 FEG TEM/STEM with inner and outer collection angles of 35mrad and lOOmrad. The specimen (6) was a cross section of singlecrystal Si containing: amorphous Si (region A), defective Si containing many stacking faults (B), two coherent Ge layers (CI; C2), and a contamination layer (D). CBED patterns (fig. lb), PEELS spectra, and HAADF signals (fig. lc) were collected at 106K and 300K along the indicated line.

Silicon layers grown over SiO2 by liquid phase epitaxy: Electron Microscopical study

1990 ◽  
Vol 48 (4) ◽  
pp. 566-567
Author(s):  
F. Banhart ◽  
F.O. Phillipp ◽  
R. Bergmann ◽  
E. Czech ◽  
M. Konuma ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Liquid Phase ◽  
Plasma Etching ◽  
Liquid Phase Epitaxy ◽  
Three Dimensional ◽  
Microscopical Study ◽  
Sample Temperature ◽  
Structural Defects ◽  
Si Substrates ◽  
Etched Surface

Defect-free silicon layers grown on insulators (SOI) are an essential component for future three-dimensional integration of semiconductor devices. Liquid phase epitaxy (LPE) has proved to be a powerful technique to grow high quality SOI structures for devices and for basic physical research. Electron microscopy is indispensable for the development of the growth technique and reveals many interesting structural properties of these materials. Transmission and scanning electron microscopy can be applied to study growth mechanisms, structural defects, and the morphology of Si and SOI layers grown from metallic solutions of various compositions.The treatment of the Si substrates prior to the epitaxial growth described here is wet chemical etching and plasma etching with NF3 ions. At a sample temperature of 20°C the ion etched surface appeared rough (Fig. 1). Plasma etching at a sample temperature of −125°C, however, yields smooth and clean Si surfaces, and, in addition, high anisotropy (small side etching) and selectivity (low etch rate of SiO2) as shown in Fig. 2.

Dechannealing Study of Nanocrystalline Si:H Layers Produced by High Dose Hydrogen Irradiation of Silicon Crystals

1998 ◽  
Vol 536 ◽  
Author(s):  
V. P. Popov ◽  
A. K. Gutakovsky ◽  
I. V. Antonova ◽  
K. S. Zhuravlev ◽  
E. V. Spesivtsev ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Rutherford Backscattering Spectrometry ◽  
Nanocrystalline Structure ◽  
Structural Defects ◽  
High Dose ◽  
Silicon Crystals ◽  
Strong Energy ◽  
Transmission Electron ◽  
Hydrogen Implantation

AbstractA study of Si:H layers formed by high dose hydrogen implantation (up to 3x107cm-2) using pulsed beams with mean currents up 40 mA/cm2 was carried out in the present work. The Rutherford backscattering spectrometry (RBS), channeling of He ions, and transmission electron microscopy (TEM) were used to study the implanted silicon, and to identify the structural defects (a-Si islands and nanocrystallites). Implantation regimes used in this work lead to creation of the layers, which contain hydrogen concentrations higher than 15 at.% as well as the high defect concentrations. As a result, the nano- and microcavities that are created in the silicon fill with hydrogen. Annealing of this silicon removes the radiation defects and leads to a nanocrystalline structure of implanted layer. A strong energy dependence of dechanneling, connected with formation of quasi nanocrystallites, which have mutual small angle disorientation (<1.50), was found after moderate annealing in the range 200-500°C. The nanocrystalline regions are in the range of 2-4 nm were estimated on the basis of the suggested dechanneling model and transmission electron microscopy (TEM) measurements. Correlation between spectroscopic ellipsometry, visible photoluminescence, and sizes of nanocrystallites in hydrogenated nc-Si:H is observed.

Dental Development in Children After Chemotherapy

2017 ◽  
Vol 68 (6) ◽  
pp. 1397-1400
Author(s):  
Cristina Bica ◽  
Mihaela Chincesan ◽  
Daniela Esian ◽  
Krisztina Martha ◽  
Valentin Ion ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Tooth Development ◽  
Lymphoblastic Leukemia ◽  
Treatment Method ◽  
Paediatric Oncology ◽  
Structural Defects ◽  
Dental Development ◽  
Cytostatic Agents ◽  
Dental Abnormalities ◽  
Tooth Buds

Chemotherapy, as a treatment method in paediatric oncology, coincides with the physiological process of tooth development. The interference between cytostatic agents and the cycle of the cells with specialised functions in the formation and mineralisation of dental structures leads to the appearance of abnormalities in the development of the tooth buds, structural defects and disorderly eruption. We have looked into the distribution of developmental tooth disorders in a group of children suffering from malignant ailments. The study reveals a high occurrence of microdontia and agenesis of premolars among children diagnosed with high-risk acute lymphoblastic leukemia at the age between 1 and 6, as well as tooth eruption disturbances in 70% of the children. The nature and the severity of dental abnormalities depend on the type of cytostatic medication, the dosage and the frequency of therapeutic cycles, the age of the child at the beginning of the oncological therapy, as well as on the stage of the odontogenesis.

The Influence of Isothermal Annealing and Structural Defects on Properties of Amorphous Fe78Si11B11 with High Magnetization Saturation

2017 ◽  
Vol 68 (3) ◽  
pp. 478-482 ◽  
Author(s):  
Katarzyna Bloch
Keyword(s):  
Numerical Analysis ◽  
Thermal Treatment ◽  
Saturation Magnetization ◽  
Isothermal Annealing ◽  
Diffusion Processes ◽  
Structural Defects ◽  
High Saturation Magnetization ◽  
Magnetization Curves ◽  
Magnetization Saturation ◽  
Very High

This paper presents the results of numerical analysis of the primary magnetization curves, which were obtained under the assumptions of the theory of approach to ferromagnetic saturation described in by H. Kronm�ller. Test samples of the Fe78Si11B11 alloy were tape-shaped materials, which were subjected to isothermal annealing, not causing their crystallization. The investigated ribbons (tapes) were characterized by a very high saturation magnetization value of approximately 2T, which the thermal treatment has increased by about 10%. It was found that reason for the change of saturation magnetization of the investigated samples was the local rearrangement of atoms due to diffusion processes leading to the release of free volumes to the surface and combining of them into larger unstable defects called pseudodislocational dipoles.

Cardiovascular Imaging for Guiding Interventional Therapy in Structural Heart Diseases

2020 ◽  
Vol 16 (2) ◽  
pp. 111-122
Author(s):  
Nora Rat ◽  
Iolanda Muntean ◽  
Diana Opincariu ◽  
Liliana Gozar ◽  
Rodica Togănel ◽  
...  
Keyword(s):  
Heart Diseases ◽  
Interventional Procedure ◽  
Imaging Techniques ◽  
Ductus Arteriosus ◽  
Three Dimensional ◽  
High Specificity ◽  
Interventional Therapy ◽  
Structural Defects ◽  
Imaging Method ◽  
Three Dimensional Echocardiography

Development of interventional methods has revolutionized the treatment of structural cardiac diseases. Given the complexity of structural interventions and the anatomical variability of various structural defects, novel imaging techniques have been implemented in the current clinical practice for guiding the interventional procedure and for selection of the device to be used. Three– dimensional echocardiography is the most used imaging method that has improved the threedimensional assessment of cardiac structures, and it has considerably reduced the cost of complications derived from malalignment of interventional devices. Assessment of cardiac structures with the use of angiography holds the advantage of providing images in real time, but it does not allow an anatomical description. Transesophageal Echocardiography (TEE) and intracardiac ultrasonography play major roles in guiding Atrial Septal Defect (ASD) or Patent Foramen Ovale (PFO) closure and device follow-up, while TEE is the procedure of choice to assess the flow in the Left Atrial Appendage (LAA) and the embolic risk associated with a decreased flow. On the other hand, contrast CT and MRI have high specificity for providing a detailed description of structure, but cannot assess the flow through the shunt or the valvular mobility. This review aims to present the role of modern imaging techniques in pre-procedural assessment and intraprocedural guiding of structural percutaneous interventions performed to close an ASD, a PFO, an LAA or a patent ductus arteriosus.

Photoluminescence and Magnetic Properties of Undoped and (Mn, Co) co-doped ZnO Nanoparticles

2020 ◽  
Vol 16 (4) ◽  
pp. 655-666
Author(s):  
Mona Rekaby
Keyword(s):  
Magnetic Properties ◽  
Zno Nanoparticles ◽  
Room Temperature ◽  
Magnetic Measurements ◽  
Structural Defects ◽  
Ferromagnetic Behavior ◽  
Secondary Phases ◽  
Antiferromagnetic Ordering ◽  
Doped Zno ◽  
Co Doped

Objective: The influence of Manganese (Mn2+) and Cobalt (Co2+) ions doping on the optical and magnetic properties of ZnO nanoparticles was studied. Methods: Nanoparticle samples of type ZnO, Zn0.97Mn0.03O, Zn0.96Mn0.03Co0.01O, Zn0.95Mn0.03 Co0.02O, Zn0.93Mn0.03Co0.04O, and Zn0.91Mn0.03Co0.06O were synthesized using the wet chemical coprecipitation method. Results: X-ray powder diffraction (XRD) patterns revealed that the prepared samples exhibited a single phase of hexagonal wurtzite structure without any existence of secondary phases. Transmission electron microscope (TEM) images clarified that Co doping at high concentrations has the ability to alter the morphologies of the samples from spherical shaped nanoparticles (NPS) to nanorods (NRs) shaped particles. The different vibrational modes of the prepared samples were analyzed through Fourier transform infrared (FTIR) measurements. The optical characteristics and structural defects of the samples were studied through Photoluminescence (PL) spectroscopy. PL results clarified that Mn2+ and Co2+ doping quenched the recombination of electron-hole pairs and enhanced the number of point defects relative to the undoped ZnO sample. Magnetic measurements were carried out at room temperature using a vibrating sample magnetometer (VSM). (Mn, Co) co-doped ZnO samples exhibited a ferromagnetic behavior coupled with paramagnetic and weak diamagnetic contributions. Conclusion: Mn2+ and Co2+ doping enhanced the room temperature Ferromagnetic (RTFM) behavior of ZnO. In addition, the signature for antiferromagnetic ordering between the Co ions was revealed. Moreover, a strong correlation between the magnetic and optical behavior of the (Mn, Co) co-doped ZnO was analyzed.

In(Ga)N Nanowire Heterostructures and Optoelectronic Device Applications

2011 ◽  
Vol 1 (2) ◽  
pp. 123-139
Author(s):  
Saeed Fathololoumi ◽  
Hieu P. T. Nguyen ◽  
Zetian Mi
Keyword(s):  
Optoelectronic Device ◽  
Nanowire Heterostructures ◽  
Device Applications
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