Ion Channeling Analysis of Disorder

1980 ◽  
Vol 2 ◽  
Author(s):  
S. T. Picraux
Keyword(s):  
Single Type ◽  
Hydrogen Trapping ◽  
Impurity Atoms ◽  
Ion Channeling ◽  
Host Atom ◽  
Direct Scattering ◽  
Wide Range ◽  
Scattering Factor ◽  
Defect Densities ◽  
High Defect Densities

ABSTRACTThe use of ion channeling to characterize disorder in semiconductors is briefly reviewed. At high defect densities the ion channeling/backscattering technique can give the depth distribution of defects with a resolution ∼ 10 nm. Quantitative analysis of the defect depth profile requires that a single type of defect dominates the scattering of partiicles out of channeling trajectories. This scattering process is characterized by two defect-specific quantities: the direct scattering factor and the dechanneling cross-section. For impurity-associated defects the lattice location of the impurity atoms can be determined to within ∼ 0.1 Å by simultaneously measuring the impurity and host atom signals as a function of tilt angle about channeling directions. The channeling technique can detect a wide range of intrinsic defects including interstitials, dislocations, stacking faults, microtwins, and amorphous clusters. Examples of the application of channeling to study defects in silicon will be given for the cases: 1) hydrogen trapping at defects; 2) ion implantation doping; and 3) epitaxial growth of layers.

Engineering high-defect densities across vertically-aligned graphene nanosheets to induce photocatalytic reactivity

Carbon ◽  
2020 ◽  
Vol 168 ◽  
pp. 32-41 ◽  
Author(s):  
Albert Guirguis ◽  
Shyam R. Polaki ◽  
Gopinath Sahoo ◽  
Subrata Ghosh ◽  
Mohammed Kamruddin ◽  
...  
Keyword(s):  
Graphene Nanosheets ◽  
Vertically Aligned ◽  
Defect Densities ◽  
High Defect Densities

Estimation of Eucalyptus delegatensis wood properties by near infrared spectroscopy

2001 ◽  
Vol 31 (10) ◽  
pp. 1671-1675 ◽  
Author(s):  
L R Schimleck ◽  
R Evans ◽  
J Ilic
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Microfibril Angle ◽  
Nir Spectroscopy ◽  
Wood Properties ◽  
Raw Material ◽  
Modulus Of Rupture ◽  
Single Type ◽  
Wide Range ◽  
Eucalyptus Delegatensis

The use of calibrated near infrared (NIR) spectroscopy for the prediction of a range solid wood properties is described. The methods developed are applicable to large-scale nondestructive forest resource assessment and to tree breeding and silvicultural programs. A series of Eucalyptus delegatensis R.T. Baker (alpine ash) samples were characterized in terms of density, longitudinal modulus of elasticity (EL), microfibril angle (MFA), and modulus of rupture (MOR). NIR spectra were obtained from the radial–longitudinal face of each sample and used to generate calibrations for the measured physical properties. The relationships were good in all cases, with coefficients of determination ranging from 0.77 for MOR through 0.90 for EL to 0.93 for stick density. In view of the rapidly expanding range of applications for this technique, it is concluded that appropriately calibrated NIR spectroscopy could form the basis of a "universal" testing instrument capable of predicting a wide range of product properties from a single type of spectrum obtained from the product or from the raw material.

scholarly journals Genomic Analysis and Comparison of Two Gonorrhea Outbreaks

mBio ◽  
2016 ◽  
Vol 7 (3) ◽  
Author(s):  
Xavier Didelot ◽  
Janina Dordel ◽  
Lilith K. Whittles ◽  
Caitlin Collins ◽  
Nicole Bilek ◽  
...  
Keyword(s):  
United Kingdom ◽  
Genome Sequencing ◽  
Transmitted Disease ◽  
Control Measures ◽  
Health Concern ◽  
Single Type ◽  
Recent Common Ancestor ◽  
Data Sets ◽  
Most Recent Common Ancestor ◽  
Wide Range

ABSTRACT Gonorrhea is a sexually transmitted disease causing growing concern, with a substantial increase in reported incidence over the past few years in the United Kingdom and rising levels of resistance to a wide range of antibiotics. Understanding its epidemiology is therefore of major biomedical importance, not only on a population scale but also at the level of direct transmission. However, the molecular typing techniques traditionally used for gonorrhea infections do not provide sufficient resolution to investigate such fine-scale patterns. Here we sequenced the genomes of 237 isolates from two local collections of isolates from Sheffield and London, each of which was resolved into a single type using traditional methods. The two data sets were selected to have different epidemiological properties: the Sheffield data were collected over 6 years from a predominantly heterosexual population, whereas the London data were gathered within half a year and strongly associated with men who have sex with men. Based on contact tracing information between individuals in Sheffield, we found that transmission is associated with a median time to most recent common ancestor of 3.4 months, with an upper bound of 8 months, which we used as a criterion to identify likely transmission links in both data sets. In London, we found that transmission happened predominantly between individuals of similar age, sexual orientation, and location and also with the same HIV serostatus, which may reflect serosorting and associated risk behaviors. Comparison of the two data sets suggests that the London epidemic involved about ten times more cases than the Sheffield outbreak. IMPORTANCE The recent increases in gonorrhea incidence and antibiotic resistance are cause for public health concern. Successful intervention requires a better understanding of transmission patterns, which is not uncovered by traditional molecular epidemiology techniques. Here we studied two outbreaks that took place in Sheffield and London, United Kingdom. We show that whole-genome sequencing provides the resolution to investigate direct gonorrhea transmission between infected individuals. Combining genome sequencing with rich epidemiological information about infected individuals reveals the importance of several transmission routes and risk factors, which can be used to design better control measures.

Status of the Atlas Elektronik’s Modular AUV Family

2006 ◽  
Author(s):  
Willi Hornfeld
Keyword(s):  
Autonomous Underwater Vehicles ◽  
Leading Edge ◽  
Cost Effective ◽  
Control Site ◽  
Single Type ◽  
Quality Of Data ◽  
Diving Depth ◽  
Sea Bed ◽  
Wide Range ◽  
Logistic Support

As opposed to ROVs (Remotely Operated Vehicles), self-propelled, unmanned autonomous underwater vehicles (AUVs) are becoming increasingly important since, unlike ROVs they can operate completely self-sufficiently, i.e. independent of the carrier platform and cable at practically any depth and for long periods of time, require only minor technical and logistic support and can be used in regions which are inaccessible to manned submersibles or ROVs (e.g. under ice regions). In other words, AUVs are distinguished by a wide range of applications, the extremely high quality of data collected, their very cost-effective operation and the large standoff capability to the carrier platform, the latter bringing about a distinct improvement in terms of carrier platform safety e.g. for military missions. Due to these advantages over conventional systems, AUVs can be employed for a whole variety of applications, such as the following in the commercial sector: • Sea Bed Mapping, • Pipeline and Route Survey, • Inspection/Control, • Site Clearance, • Debris Survey, • Science – Search – Environment – Geology, • Harbour and ship’s hull inspection. Moreover AUVs will play an important role in the military scenario like mine countermeasure as well. Obviously, one single type of AUV will be unable to cover this entire spectrum if — above and beyond the aforementioned applications — one considers the different operating depths ranging from coastal regions (about 10 m) to deep water (approx. 4000 m) and the various possible carrier platforms (helicopters, ships, submarines, shore stations). On the other hand, the development and use of one specific type of AUV for one or a very limited number of mission types would be very expensive, both in terms of costs involved and necessary logistics, and would hardly be acceptable on the market. The solution to this problem is the “modularity” of the AUV subsystems as well as a family concept for the vehicle design. To implement this strategy, ATLAS ELEKTRONIK has forced the development and marketing of an AUV family for a wide array of missions. The family starts with the SeaFox-IQ, a very small and lightweight (40 kg) AUV for 300 m diving depth, based on the extreme successful mine disposal ROV SeaFox. The big brother is the SeaStout, a 100 kg AUV, designed for 300 m too. The SeaOtter Mk1 and SeaOtter Mk2 AUVs are 1500 kg and 1100 kg vehicles for 600 m operations. The leading edge is the AUV DeepC, a 2500 kg experimental vehicle developed for 4000 m depth and up to 60 h endurance. The ATLAS AUV family offer a lot of hard- and software commonality to ensure that serviceability is maintained, while having a high degree of “customisation” in key areas like payload sensor selection ensuring they will meet customer needs.

scholarly journals Associations Between Multiple Leisure Activities, Mental Health and Substance Use Among Adolescents in Denmark: A Nationwide Cross-Sectional Study

2020 ◽  
Vol 14 ◽  
Author(s):  
Ziggi Ivan Santini ◽  
Charlotte Meilstrup ◽  
Carsten Hinrichsen ◽  
Line Nielsen ◽  
Ai Koyanagi ◽  
...  
Keyword(s):  
Mental Health ◽  
Substance Use ◽  
Mental Health Problems ◽  
Leisure Activities ◽  
Leisure Activity ◽  
Well Being ◽  
Single Type ◽  
Cross Sectional ◽  
Wide Range ◽  
Activity Types

Background: Previous research has suggested that leisure activity may benefit mental health and protect against substance use among adolescents, but more research is needed to asses associations with a wide range of outcomes. The aim of this study was to assess associations between multiple leisure activities and (1) mental health outcomes and (2) substance use outcomes in a sample of Danish adolescents.Methods: Using data from the Danish part of the European School Survey Project on Alcohol and Other Drugs (ESPAD) collected in 2019, nation-wide cross-sectional data from 2,488 participants aged 15 or 16 in Denmark were analyzed to assess associations between number of leisure activity types and outcomes pertaining to mental health and substance use.Results: Our results show that engaging in multiple activity types at least once a week—as compared to one single type of activity—is associated with increased odds for high mental well-being, and reduced odds for mental health problems. Engaging in multiple activity types is also associated with reduced odds for overall substance use and for using substances as a coping method. Among those using substances, engaging in multiple activity types is associated with reduced odds of above average substance use.Conclusion: Increasing opportunities for adolescents to engage in leisure activities is suggested to be useful in enhancing mental health and preventing substance use and promoting mental health. Promoting and increasing access to leisure activities among adolescents could be a promising avenue for policy and practice.

Electrical Stability Impact of Gate Oxide in Channel Implanted SiC NMOS and PMOS Transistors

2017 ◽  
Vol 897 ◽  
pp. 513-516 ◽  
Author(s):  
Muhammad I. Idris ◽  
Ming Hung Weng ◽  
H.K. Chan ◽  
A.E. Murphy ◽  
Dave A. Smith ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Gate Oxide ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Single Type ◽  
Electrical Stability ◽  
Wide Range ◽  
Flatband Voltage ◽  
The Impact

Operation of SiC MOSFETs beyond 300°C opens up opportunities for a wide range of CMOS based digital and analogue applications. However the majority of the literature focuses only on the optimization of a single type of MOS device (either PMOS or more commonly NMOS) and there is a lack of a comprehensive study describing the challenge of optimizing CMOS devices. This study reports on the impact of gate oxide performance in channel implanted SiC on the electrical stability for both NMOS and PMOS capacitors and transistors. Parameters including interface state density (Dit), flatband voltage (VFB), threshold voltage (VTH) and effective charge (NEFF) have been acquired from C-V characteristics to assess the effectiveness of the fabrication process in realising high quality gate dielectrics. The performance of SiC based CMOS transistors were analyzed by correlating the characteristics of the MOS interface properties, the MOSFET 1/f noise performance and transistor on-state stability at 300°C. The observed instability of PMOS devices is more significant than in equivalent NMOS devices. The results from MOS capacitors comprising interface state density (Dit), flatband voltage (VFB), threshold voltage (VTH) for both N and P MOS are in agreement with the expected characteristics of the respective transistors.

Effect of C/Si Ratio and Nitrogen Doping on 4H-SiC Epitaxial Growth Using Dichlorosilane Precursor

2015 ◽  
Vol 821-823 ◽  
pp. 129-132 ◽  
Author(s):  
Hai Zheng Song ◽  
M.V.S. Chandrashekhar ◽  
T.S. Sudarshan
Keyword(s):  
Growth Rate ◽  
Epitaxial Growth ◽  
Nitrogen Doping ◽  
Gas Flow ◽  
Gas Flow Rate ◽  
Wide Range ◽  
N Doping ◽  
Morphological Defects ◽  
Defect Densities ◽  
Epilayer Surface

Application of dichlorosilane (DCS) in 4H-SiC epitaxial growth on 4° off-cut substrates has been studied. The effect of C/Si ratio and N2gas flow rate on epilayer properties is investigated in detail. It is found that the C/Si ratio has a significant influence on the growth rate, epilayer surface roughness (step-bunching), conversion of basal plane dislocations (BPDs), and generation of morphological defects and in-grown stacking faults. A wide range of doping concentration from p- to n+ can be controlled in DCS growth. High quality 4° off-cut SiC epilayers are achieved for C/Si=1.3 – 1.8. Addition of N2has no obvious influence on growth rate and defect densities. The BPD conversion greater than 99.8% is achieved independent of N doping without any pretreatment.

Defect Formation and Hydrogen Trapping in H+ Implanted FZ Silicon

1984 ◽  
Vol 36 ◽  
Author(s):  
W. J. Choyke ◽  
J. A. Spitznagel ◽  
N. J. Doyle ◽  
S. Wood ◽  
R. B. Irwin
Keyword(s):  
Defect Formation ◽  
Damage Zone ◽  
Dislocation Loops ◽  
Hydrogen Trapping ◽  
Temperature Dependent ◽  
Ion Channeling ◽  
Float Zone ◽  
Transmission Electron ◽  
Amorphous Zone ◽  
Post Implantation

ABSTRACTThe formation and annealing of buried damage layers in hydrogen implanted N-type float zone <111> silicon has been studied by Rutherford Backscattering/ion channeling and cross-section transmission electron microscopy. Implantation with 50 keV or 75 keV H+ ions was conducted at temperatures of 95K, 300K and 800K at fluences of 2×1017 H+/cm2, 8×1017 H+/cm2 and 1×1018 H+/cm2. Post implantation annealing was conducted at temperatures up to 800K. The results show a temperature dependent transition from a highly hydrogen doped amorphous zone bounded by strongly diffracting (TEM) 2–5 nm diameter defects for implantation at 95K to a crystalline microstructure containing small dislocation loops and ∼40% of the implanted hydrogen for implantation at 300K. Defect production and annealing and hydrogen trapping in the damage zone are shown to depend on the relative implantation and post implantation annealing temperatures.

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