Interstitial Trapped Hydrogen Molecules in Pecvdamorphous Silicon

1999 ◽  
Vol 557 ◽  
Author(s):  
R. Borzi ◽  
F. Mascarenhas ◽  
P. A. Fedders ◽  
D. J. Leopold ◽  
R. E. Norberg ◽  
...  
Keyword(s):  
Activation Energy ◽  
Molecular Hydrogen ◽  
Pulse Sequences ◽  
High Quality ◽  
Hopping Transport ◽  
Hydrogen Molecules ◽  
Order Of Magnitude ◽  
Si Films ◽  
Molecular Components ◽  
Radiofrequency Pulse

AbstractNew NMR measurements show that interstitial T site-trapped molecular hydrogen can amount to more than one third of the contained hydrogen in high quality PECVD amorphous silicon. Microvoid-contained dense molecular hydrogen is negligible in these good films. Experiments on a sequence of hydrogenated and/or deuterated a-Si films have characterized individually-trapped molecular HD and D2 in films deposited from SiD4, and from SiH4+D2. The T site-trapped molecular hydrogen fraction observed here is larger than previously reported because of recent efforts to measure very slowly relaxing molecular components and the employment of radiofrequency pulse sequences to detect ortho-D2 with nuclear spin I=2. The population of interstitially trapped molecular hydrogen increases with increasing photovoltaic quality over a range of an order of magnitude in photoresponse product ημτ. Above 200 K, hopping transport of molecular hydrogen among the amorphous equivalent of interstitial T sites occurs with an activation energy near 50 meV.

Time-of-Flight Measurement on a-Ge:H and a-SiGe:H Alloys

1992 ◽  
Vol 258 ◽  
Author(s):  
E.Z. Liu ◽  
D. Pang ◽  
W. Paul ◽  
J.H. Chen
Keyword(s):  
Room Temperature ◽  
Transport Model ◽  
Drift Mobility ◽  
Band Tail ◽  
High Quality ◽  
Hopping Transport ◽  
Flight Measurement ◽  
Order Of Magnitude ◽  
Temperature Ranges ◽  
Electron Drift Mobility

ABSTRACTWe report TOF measurements on high quality intrinsic a-Ge:H and a-SiGe:H films of E04=1–4.eV in temperature ranges of 200 to 280 and 230 to 300K, respectively. Complete charge collection is achieved in all measurements. For a-Ge:H films, the (μτ)e product obtained from the Hecht plot is (5±3)×10-8 cm2/V above 240K and decreases at lower temperatures. The electron transit signal is dispersive at all temperatures. The a obtained from ttV-1/αis 0.23 at 200K and approaches 1.0 at 260K. The electron drift mobility μd shows activated behavior, with an energy of 0.37±0.05eV, and has an extrapolated room temperature value of 0.03 cm2/Vs. Compared to a-Ge:H, μd of a-SiGe:H alloy samples is lower by one order of magnitude but has a similar activation energy. These results are consistent with a band tail hopping transport model.

Symmetry principles for the design of radiofrequency pulse sequences in the nuclear magnetic resonance of rotating solids

2000 ◽  
Vol 321 (3-4) ◽  
pp. 205-215 ◽  
Author(s):  
Marina Carravetta ◽  
Mattias Edén ◽  
Xin Zhao ◽  
Andreas Brinkmann ◽  
Malcolm H Levitt
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Pulse Sequences ◽  
Symmetry Principles ◽  
Radiofrequency Pulse ◽  
Nuclear Magnetic

MAGNETIC RESISTIVITY IN Bi2Sr2Ca(Cu1-xCox)2Od EPITAXIAL THIN FILMS

2007 ◽  
Vol 21 (01) ◽  
pp. 127-132
Author(s):  
T. R. YANG ◽  
G. ILONCA ◽  
V. TOMA ◽  
P. BALINT ◽  
M. BODEA
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Activation Energy ◽  
Glass Transition ◽  
Effective Activation Energy ◽  
Epitaxial Thin Films ◽  
Effective Activation ◽  
High Quality ◽  
Plastic Deformations ◽  
Magnetic Resistivity

The scaling behavior of the effective activation energy of high-quality epitaxial c-oriented Bi 2 Sr 2 Ca ( Cu 1-x Co x)2 O d thin films with 0≤x ≤0.025 has been studied as a function of temperature and magnetic field. For all samples, the effective activation energy scales as U(T, μoH)=Uo(1-T/T c )mHn with exponent m=1.25±0.03, n=-1/2 and the field scaling 1/μoH and -UμoH for thick films and ultra thin films, respectively. The results are discussed taking into account of the influence of the Co substitution with a model in which U(T, H) arises from plastic deformations of the viscous flux liquid above the vortex-glass transition temperature.

scholarly journals Toward Cost-Effective Manufacturing of Silicon Solar Cells: Electrodeposition of High-Quality Si Films in a CaCl2-based Molten Salt

2017 ◽  
Vol 56 (47) ◽  
pp. 15078-15082 ◽  
Author(s):  
Xiao Yang ◽  
Li Ji ◽  
Xingli Zou ◽  
Taeho Lim ◽  
Ji Zhao ◽  
...  
Keyword(s):  
Solar Cells ◽  
Molten Salt ◽  
Cost Effective ◽  
Silicon Solar Cells ◽  
High Quality ◽  
Si Films

scholarly journals Diffracted Light Contrast: Improving the Resolution of a Basic Light Microscope by an Order of Magnitude

2006 ◽  
Vol 14 (6) ◽  
pp. 10-15
Author(s):  
W. Barry Piekos
Keyword(s):  
Epithelial Cells ◽  
Light Microscope ◽  
Depth Of Field ◽  
High Quality ◽  
Surface Lattice ◽  
Buccal Epithelial Cells ◽  
Order Of Magnitude ◽  
Student Laboratory ◽  
Light Contrast ◽  
Very High

The discovery that the diffracted light from a convex edge can be used to form a very high-quality, shadowcast image on any light microscope has led to a device and method, diffracted-light contrast (DLC), which will allow shadowcast imaging to be routinely performed on student/laboratory microscopes (Piekos, 1999, 2003). The surface lattice of Surirella gema was easily resolved, and micrographs comparing the subcellular details of buccal epithelial cells viewed with DLC vs. Nomarski DIC showed that, on the microscopes used, DLC was superior in both the detail it rendered and depth of field. Although the images presented revealed DLC to be an excellent technique, the full capabilities of the technique were not known at the time.

scholarly journals SYNTHESIS AND ELECTRICAL CONDUCTIVITY OF SOLID SOLUTIONS OF THE SYSTEM RbF-PbF2-SnF2

2019 ◽  
Vol 85 (5) ◽  
pp. 60-68
Author(s):  
Yuliay Pogorenko ◽  
Anatoliy Omel’chuk ◽  
Roman Pshenichny ◽  
Anton Nagornyi
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Temperature Dependence ◽  
Solid Solutions ◽  
Basic Structure ◽  
Elementary Cell ◽  
Initial Structure ◽  
Fluoride Ions ◽  
Temperature Range ◽  
Order Of Magnitude

In the system RbF–PbF2–SnF2 are formed solid solutions of the heterovalent substitution RbxPb0,86‑xSn1,14F4-x (0 < x ≤ 0,2) with structure of β–PbSnF4. At x > 0,2 on the X-ray diffractograms, in addition to the basic structure, additional peaks are recorded that do not correspond to the reflexes of the individual fluorides and can indicate the formation of a mixture of solid solutions of different composition. For single-phase solid solutions, the calculated parameters of the crystal lattice are satisfactorily described by the Vegard rule. The introduction of ions of Rb+ into the initial structure leads to an increase in the parameter a of the elementary cell from 5.967 for x = 0 to 5.970 for x = 0.20. The replacement of a part of leads ions to rubium ions an increase in electrical conductivity compared with β–PbSnF4 and Pb0.86Sn1.14F4. Insignificant substitution (up to 3.0 mol%) of ions Pb2+ at Rb+ at T<500 K per order of magnitude reduces the conductivity of the samples obtained, while the nature of its temperature dependence is similar to the temperature dependence of the conductivity of the sample β-PbSnF4. By replacing 5 mol. % of ions with Pb2+ on Rb+, the fluoride ion conductivity at T> 450 K is higher than the conductivity of the initial sample Pb0,86Sn1,14F4 and at temperatures below 450 K by an order of magnitude smaller. With further increase in the content of RbF the electrical conductivity of the samples increases throughout the temperature range, reaching the maximum values at x≥0.15 (σ573 = 0.34–0.41 S/cm, Ea = 0.16 eV and σ373 = (5.34–8.16)•10-2 S/cm, Ea = 0.48–0.51 eV, respectively). In the general case, the replacement of a part of the ions of Pb2+ with Rb+ to an increase in the electrical conductivity of the samples throughout the temperature range. The activation energy of conductivity with an increase in the content of RbF in the low-temperature region in the general case increases, and at temperatures above 400 K is inversely proportional decreasing. The nature of the dependence of the activation energy on the concentration of the heterovalent substituent and its value indicate that the conductivity of the samples obtained increases with an increase in the vacancies of fluoride ions in the structure of the solid solutions.

Effect of Ge on SiC Film Morphology in SiC/Si Films Grown by MOCVD

1999 ◽  
Vol 572 ◽  
Author(s):  
W. L. Samey ◽  
L. Salamanca-Riba ◽  
P. Zhou ◽  
M. G. Spencer ◽  
C. Taylor ◽  
...  
Keyword(s):  
Stacking Faults ◽  
Two Dimensional ◽  
High Quality ◽  
Flow Rates ◽  
Si Substrates ◽  
Cvd Growth ◽  
Polytype Transformation ◽  
Si Films ◽  
Sic Film ◽  
Sic Films

ABSTRACTSiC/Si films generally contain stacking faults and amorphous regions near the interface. High quality SiC/Si films are especially difficult to obtain since the temperatures usually required to grow high quality SiC are above the Si melting point. We added Ge in the form of GeH2 to the reactant gases to promote two-dimensional CVD growth of SiC films on (111) Si substrates at 1000°C. The films grown with no Ge are essentially amorphous with very small crystalline regions, whereas those films grown with GeH2 flow rates of 10 and 15 sccm are polycrystalline with the 3C structure. Increasing the flow rate to 20 sccm improves the crystallinity and induces growth of 6H SiC over an initial 3C layer. This study presents the first observation of spontaneous polytype transformation in SiC grown on Si by MOCVD.

Abstract 15240: Evaluation of the Performance and Safety of Wideband Cardiac MRI in Patients With a Cardiac Implantable Electronic Device (CIED)

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Sarah M Schwartz ◽  
Ashitha Pathrose ◽  
Ali Serhal ◽  
Ryan Avery ◽  
Ann Ragin ◽  
...  
Keyword(s):  
Image Quality ◽  
Electronic Device ◽  
Pulse Sequences ◽  
Free Breathing ◽  
Whole Body ◽  
Breath Hold ◽  
Single Shot ◽  
Before And After ◽  
Order Of Magnitude ◽  
Chest X Ray

Introduction: Wideband late gadolinium enhancement (LGE) CMR is capable of suppressing image artifacts induced by cardiac implanted electronic devices (CIEDs). We implemented our own wideband segmented (seg) breath-hold and wideband single-shot (SS) free-breathing LGE pulse sequences and used them clinically since 2016. The purpose of this study was to evaluate image quality and CMR safety of wideband LGE compared to standard LGE. Methods: We retrospectively identified 54 consecutive patients (mean age: 61±15 years; 31% females) with CIED (33 t-ICD, 4 s-ICD, 15 pacemaker, 1 CRT-D, 1 CRT-P) who underwent CMR at 1.5T (Avanto, Siemens). Standard seg, wideband seg, and wideband SS LGE used standard imaging parameters. 16 myocardial segments were scored for scar/myocardial conspicuity and presence of any visual artifact on a 5-point Likert scale (1:worst; 3:acceptable; 5:best). Distance between center of the heart and CIED (CXR D) was measured on chest X-ray. Whole-body specific absorption rate (SAR) was read from DICOM metadata. Device changes were calculated from pre- and post- device interrogation measurements. Results: Both wideband seg and SS LGE consistently produced better image quality than standard LGE (Figure 1A). Median conspicuity and artifact scores were significantly better for wideband seg (F=20.6, p<0.001) and wideband SS (F=24.2, p<0.001) LGE compared to standard LGE. There was a trend in conspicuity and artifact scores with CIED distance for standard LGE (rho=0.476, p=0.02), but not wideband LGE scans (Figure 1B, 1C). Whole-body SAR averaged for both wideband scans (0.15±0.04 W/kg) was one order of magnitude below the 2.0 W/kg FDA limit. Device parameters (sensing, impedance, threshold, battery level) did not differ before and after CMR including wideband LGE. Conclusions: Both wideband seg and SS LGE scans produced improved image quality compared to standard LGE while maintaining CMR safety. *The first two authors (SS and AP) contributed equally

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