Correlation Between the V-I Characteristics of (0001) 4H-SiC PN Junctions Having Different Structural Features and Synchrotron X-ray Topography

2008 ◽  
Vol 1069 ◽  
Author(s):  
Ryoji Kosugi ◽  
Toyokazu Sakata ◽  
Yuuki Sakuma ◽  
Tsutomu Yatsuo ◽  
Hirofumi Matsuhata ◽  
...  
Keyword(s):  
High Energy ◽  
Structural Features ◽  
Incidence Geometry ◽  
Voltage Source ◽  
Large Area ◽  
Chip Area ◽  
Power Mosfets ◽  
X Ray ◽  
Pn Junctions ◽  
The Difference

ABSTRACTIn practical use of the SiC power MOSFETs, further reduction of the channel resistance, high stability under harsh environments, and also, high product yield of large area devices are indispensable. Pn diodes with large chip area have been already reported with high fabrication yield, however, there is few reports in terms of the power MOSFETs. To clarify the difference between the simple pn diodes and power MOSFETs, we have fabricated four pn-type junction TEGs having the different structural features. Those pn junctions are close to the similar structure of DIMOS (Double-implanted MOS) step-by-step from the simple pn diodes. We have surveyed the V-I characteristics dependence on each structural features over the 2inch wafer. Before their fabrication, we formed grid patterns with numbering over the 2inch wafer, then performed the synchrotron x-ray topography observation. This enables the direct comparison the electrical and spectrographic characteristics of each pn junctions with the fingerprints of defects.Four structural features from TypeA to TypeD are as follows. TypeA is the most simple structure as same as the standard pn diodes formed by Al+ ion implantation (I/I), except that the Al+ I/I condition conforms to that of the p-well I/I in the DIMOS. The JTE structure was used for the edge termination on all junctions. While the TypeA consists of one p-type region, TypeB and TypeC consists of a lot of p-wells. The difference of Type B and C is a difference of the oxide between the adjacent p-wells. The oxide of TypeB consists of the thick field oxide, while that of TypeC consists of the thermal oxide corresponding to the gate oxide in the DIMOS. In the TypeD structure, n+ region corresponding to the source in the DIMOS was added by the P+ I/I. The TypeD is the same structure of the DIMOS, except that the gate and source contacts are shorted. The V-I measurements of the pn junctions are performed using the KEITHLEY 237 voltage source meters with semi-auto probe machine. An active area of the fabricated pn junctions TEGs are 150um2 and 1mm2. Concentration and thickness of the drift layer are 1e16cm−3 and 10um, respectively.In order to compare the V-I characteristics of fabricated pn junctions with their defects information that obtained from x-ray topography measurements directly, the grid patterns are formed before the fabrication. The grid patterns were formed over the 2inch wafer by the SiC etching. The synchrotron x-ray topography measurements are carried out at the Beam-Line 15C in Photon-Factory in High-Energy-Accelerator-Research-Organization. Three diffraction conditions, g=11-28, -1-128, and 1-108, are chosen in grazing-incidence geometry (improved Berg-Barrett method).In the presentation, the V-I characteristics mapping on the 2inch wafer for each pn junctions, and the comparison of V-I characteristics with x-ray topography will be reported.

scholarly journals Fermi-LAT and WMAP observations of the supernova remnant Puppis A

2013 ◽  
Vol 9 (S296) ◽  
pp. 295-299
Author(s):  
Marie-Hélène Grondin ◽  
John W. Hewitt ◽  
Marianne Lemoine-Goumard ◽  
Thierry Reposeur ◽  
Keyword(s):  
Supernova Remnants ◽  
Supernova Remnant ◽  
Gamma Ray ◽  
High Energy ◽  
Radio Spectrum ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Large Area ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Γ Ray

AbstractThe supernova remnant (SNR) Puppis A (aka G260.4-3.4) is a middle-aged supernova remnant, which displays increasing X-ray surface brightness from West to East corresponding to an increasing density of the ambient interstellar medium at the Eastern and Northern shell. The dense IR photon field and the high ambient density around the remnant make it an ideal case to study in γ-rays. Gamma-ray studies based on three years of observations with the Large Area Telescope (LAT) aboard Fermi have revealed the high energy gamma-ray emission from SNR Puppis A. The γ-ray emission from the remnant is spatially extended, and nicely matches the radio and X-ray morphologies. Its γ-ray spectrum is well described by a simple power law with an index of ~2.1, and it is among the faintest supernova remnants yet detected at GeV energies. To constrain the relativistic electron population, seven years of Wilkinson Microwave Anisotropy Probe (WMAP) data were also analyzed, and enabled to extend the radio spectrum up to 93 GHz. The results obtained in the radio and γ-ray domains are described in detail, as well as the possible origins of the high energy γ-ray emission (Bremsstrahlung, Inverse Compton scattering by electrons or decay of neutral pions produced by proton interactions).

scholarly journals Development of STJ as a New X-Ray Detector

1998 ◽  
Vol 188 ◽  
pp. 335-336
Author(s):  
N. Y. Yamasaki ◽  
T. Ohashi ◽  
K. Kikuchi ◽  
H. Miyazaki ◽  
E. Rokutanda ◽  
...  
Keyword(s):  
Energy Resolution ◽  
Effective Area ◽  
High Energy ◽  
High Energy Resolution ◽  
X Rays ◽  
Large Area ◽  
Position Resolution ◽  
X Ray ◽  
Plane Detector ◽  
Nippon Steel Corporation

STJs are promising X-ray detectors as high energy resolution spectrometers due to the small excitation energy to break the Cooper pairs to product detectable electrons. The expected energy resolution is about 5 eV for a 6 keV incident X-rays (see review by Kraus et al. and Esposito et al.). We have developed a large area (178 × 178μm2) Nb/Al/AlOX/Al/Nb STJs (Kurakado et al. 1993) and series-connected STJs with a position resolution of 35μm for α particles (Kurakado 1997) at Nippon Steel Corporation. As a focal plane detector in future X-ray missions, we are developing STJs whose targert characteristics are; an energy resolution of 20 eV at 6keV, an effective area of 1 cm2, and position resolution of 100μm.

Microstructural Properties of Common Yew and Norway Spruce Determined with Silviscan

IAWA Journal ◽  
2009 ◽  
Vol 30 (2) ◽  
pp. 165-178 ◽  
Author(s):  
Daniel Keunecke ◽  
Robert Evans ◽  
Peter Niemz
Keyword(s):  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Elastic Anisotropy ◽  
Longitudinal Direction ◽  
Structural Features ◽  
Structure Property ◽  
Tangential Plane ◽  
Cross Sectional ◽  
X Ray ◽  
The Difference

Yew wood holds a special position within the softwoods with regard to its exceptional elasto-mechanical behaviour. Despite a relatively high density, it is highly elastic in the longitudinal direction (the modulus of elasticity is low and the stretch to break high). In the radial-tangential plane, its elastic anisotropy is clearly less pronounced compared to other softwoods such as spruce. Knowledge of the anatomical organisation of yew wood is an indispensable precondition for the correct interpretation of this conspicuous mechanical behaviour. The aim of this study, therefore, was to interpret the difference in elasto-mechanical behaviour of yew and spruce (as a reference) through their relative microstructures as measured by SilviScan, a technology based on X-ray densitometry, X-ray diffractometry and optical microscopy. This system is able to measure a variety of structural features in a wood sample. The results reveal that the elasto-mechanical response of yew is primarily due to large microfibril angles and a more homogeneous cross-sectional tissue composition (regarding tracheid dimensions and density distribution) compared to spruce. With respect to structure-property relationships, it was concluded that yew wood combines properties of normal and compression wood and therefore takes an intermediate position between them.

Two new zinc(II) and mercury(II) complexes based on N,N′-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide): synthesis, crystal structures and antibacterial activities

2020 ◽  
Vol 76 (5) ◽  
pp. 476-482
Author(s):  
Al-Ameen Bariz OmarAli ◽  
Ahmed Jasim M. Al-Karawi ◽  
Adil A. Awad ◽  
Necmi Dege ◽  
Sevgi Kansız ◽  
...  
Keyword(s):  
Organic Ligand ◽  
Antibacterial Activities ◽  
Structural Features ◽  
Bacterial Strains ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
X Ray Crystallography ◽  
Growth Inhibitory ◽  
The Difference

Reaction of N,N′-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide), C20H18F2N4O2, (LF ), with zinc chloride and mercury(II) chloride produced different types and shapes of neutral coordination complexes, namely, dichlorido[N,N′-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide)-κ2 N,O]zinc(II), [ZnCl2(C20H18F2N4O2)], (1), and dichlorido[N,N′-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide)-κ4 O,N,N′,O′]mercury(II), [HgCl2(C20H18F2N4O2)], (2). The organic ligand and its metal complexes are characterized using various techniques: IR, UV–Vis and nuclear magnetic resonance (NMR) spectroscopies, in addition to powder X-ray diffraction (PXRD), single-crystal X-ray crystallography and microelemental analysis. Depending upon the data from these analyses and measurements, a typical tetrahedral geometry was confirmed for zinc complex (1), in which the ZnII atom is located outside the bis(benzhydrazone) core. The HgII atom in (2) is found within the core and has a common octahedral structure. The in vitro antibacterial activities of the prepared compounds were evaluated against two different bacterial strains, i.e. gram positive Bacillus subtilis and gram negative Pseudomonas aeruginosa bacteria. The prepared compounds exhibited differentiated growth-inhibitory activities against these two bacterial strains based on the difference in their lipophilic nature and structural features.

scholarly journals Prospects for Coordinated Observations with XTE

1995 ◽  
Vol 12 (2) ◽  
pp. 219-226 ◽  
Author(s):  
A. B. Giles ◽  
K. Jahoda ◽  
J. H. Swank ◽  
W. Zhang
Keyword(s):  
High Energy ◽  
High Time Resolution ◽  
Massachusetts Institute Of Technology ◽  
Large Area ◽  
X Ray ◽  
Transient Sources ◽  
Sky Monitor ◽  
Institute Of Technology ◽  
Proportional Counter Array ◽  
The University

AbstractThe X-ray Timing Explorer (XTE) is a NASA satellite designed to perform high-time-resolution studies of known X-ray sources. The two main experiments are a large-area proportional counter array (PCA) from the Goddard Space Flight Center (GSFC) and a high-energy X-ray timing experiment (HEXTE) from the University of California at San Diego (UCSD). The PCA data is processed by an electronic data system (EDS) built by the Massachusetts Institute of Technology (MIT) that performs many parallel processing analysis functions for on-board evaluation and data compression. MIT also provide an all-sky monitor (ASM) experiment so that XTE can be slewed rapidly to new transient sources. The spacecraft provides a mean science telemetry rate for the PCA of ~20 kilobits per second (kbps), with bursts to 256 kbps for durations of 30 minutes. Photons are tagged to 1 μs and absolute timing should be better than 100 μs. XTE is due for launch in late August 1995 and the first NASA Research Announcement (NRA) is due out in January 1995. This paper summarises XTE’s performance and then discusses the interactive and flexible operations of the satellite and some of the science it can do. These features should make XTE a productive spacecraft for coordinated observation programs.

scholarly journals High Energy Resolution X-Ray Spectrometer for High Count Rate Xrf Applications

1993 ◽  
Vol 37 ◽  
pp. 405-411
Author(s):  
C. S. Rossington ◽  
N. W. Madden ◽  
K. Chapman
Keyword(s):  
Energy Resolution ◽  
Count Rate ◽  
High Energy ◽  
Low Noise ◽  
High Energy Resolution ◽  
Photon Flux ◽  
Large Area ◽  
High Count ◽  
High Count Rate ◽  
X Ray

AbstractA new x-ray spectrometer has been constructed which incorporates a novel large area, low capacitance Si(Li) detector and a low noise JFET (junction field effect transistor) preamplifier. The spectrometer operates at high count Tates without the conventional compromise in energy resolution. For example, at an amplifier peaking time of 1 p.sec and a throughput count rate of 145,000 counts sec-1, the energy resolution at 5.9 keV is 220 eV FWHM. Commercially available spectrometers utilizing conventional geometry Si(Li) detectors with areas equivalent to the new detector have resolutions on the order of 540 eV under the same conditions. Conventional x-ray spectrometers offering high energy resolution must employ detectors with areas one-tenth the size of the new LBL detector (20 mm2 compared with 200 mm2). However, even with the use of the smaller area detectors, the energy resolution of a commercial system is typically limited to approximately 300 eV (again, at 1 μsec and 5.9 keV) due to the noise of the commercially available JFET's. The new large area detector is useful in high count rate applications, but is also useful in the detection of weak photon signals, in which it is desirable to subtend as large an angle of the available photon flux as possible, while still maintaining excellent energy resolution. X-ray fluorescence data from die new spectrometer is shown in comparison to a commercially available system in the analysis of a dilute muhi-element material, and also in conjunction with high count rate synchrotron EXAFS applications.

scholarly journals Broadband characterisation of the very intense TeV flares of the blazar 1ES 1959+650 in 2016

2020 ◽  
Vol 638 ◽  
pp. A14 ◽  
Author(s):  
◽  
V. A. Acciari ◽  
S. Ansoldi ◽  
L. A. Antonelli ◽  
A. Arbet Engels ◽  
...  
Keyword(s):  
Crab Nebula ◽  
Spectral Energy Distribution ◽  
High Energy ◽  
Spectral Energy ◽  
Proton Synchrotron ◽  
Large Area ◽  
X Ray ◽  
High Energy Peak ◽  
Energy Peak ◽  
Jet Power

1ES 1959+650 is a bright TeV high-frequency-peaked BL Lac object exhibiting interesting features like “orphan” TeV flares and broad emission in the high-energy regime that are difficult to interpret using conventional one-zone Synchrotron Self-Compton (SSC) scenarios. We report the results from the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) observations in 2016 along with the multi-wavelength data from the Fermi Large Area Telescope (LAT) and Swift instruments. MAGIC observed 1ES 1959+650 with different emission levels in the very-high-energy (VHE, E >  100 GeV) γ-ray band during 2016. In the long-term data, the X-ray spectrum becomes harder with increasing flux and a hint of a similar trend is also visible in the VHE band. An exceptionally high VHE flux reaching ∼3 times the Crab Nebula flux was measured by MAGIC on the 13 and 14 of June, and 1 July 2016 (the highest flux observed since 2002). During these flares, the high-energy peak of the spectral energy distribution (SED) lies in the VHE domain and extends up to several TeV. The spectrum in the γ-ray (both Fermi-LAT and VHE bands) and the X-ray bands are quite hard. On 13 June and 1 July 2016, the source showed rapid variations in the VHE flux within timescales of less than an hour. A simple one-zone SSC model can describe the data during the flares requiring moderate to large values of the Doppler factors (δ ≥ 30−60). Alternatively, the high-energy peak of the SED can be explained by a purely hadronic model attributed to proton-synchrotron radiation with jet power Ljet ∼ 1046 erg s−1 and under high values of the magnetic field strength (∼100 G) and maximum proton energy (∼few EeV). Mixed lepto-hadronic models require super-Eddington values of the jet power. We conclude that it is difficult to get detectable neutrino emission from the source during the extreme VHE flaring period of 2016.

Schemes to determine the crystal potential under dynamical conditions using voltage variation

1999 ◽  
Vol 55 (2) ◽  
pp. 160-167 ◽  
Author(s):  
Peter Rez
Keyword(s):  
Simple Procedure ◽  
Relativistic Effects ◽  
Single Scattering ◽  
High Energy ◽  
Dynamical Diffraction ◽  
X Ray ◽  
Crystal Potential ◽  
Voltage Variation ◽  
High Energy Electrons ◽  
The Difference

Charge densities and crystal structures can be determined routinely from X-ray diffraction as X-ray scattering is relatively weak and single scattering can be assumed. The strong dynamical diffraction of high-energy electrons has prevented electron diffraction from being used in the same way. Dynamical diffraction describes both the propagation of the Bragg diffracted wave in the crystal and the scattering by the crystal potential. The balance between these two processes changes as a function of voltage due to relativistic effects. The difference in diffracted intensities recorded at two voltages is shown to be directly proportional to the crystal potential. This is confirmed by calculations using first-order perturbation theory which show negligible differences compared to exact calculation. It should therefore be possible to use differences in intensity measured as a function of voltage to determine the crystal potential directly. If the full complex wave function is available, then there is a particularly simple procedure to recover the potential, even under dynamical conditions.

White beam X-ray Diffraction Topography (WBXDT) Studies of Bridgman Grown CdZnTe Crystals

2015 ◽  
Vol 1792 ◽  
Author(s):  
Stephen Babalola ◽  
Samuel Uba ◽  
Anwar Hossain ◽  
Giuseppe Camarda ◽  
Ralph James ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Charge Trapping ◽  
Radiation Detectors ◽  
Growth Conditions ◽  
High Energy ◽  
Infrared Transmission ◽  
X Ray Diffraction ◽  
Large Area ◽  
X Ray ◽  
White Beam

ABSTRACTCZT is a semiconductor material that promises to be a good candidate for uncooled gamma radiation detectors. However, to date, we are yet to overcome the technological difficulties in production of large size, defect-free CZT crystals. The most common problem is accumulation of Tellurium precipitates as microscopic inclusions. These inclusions influence the charge collection through charge trapping and electric field distortion. We employed high energy transmission X-ray diffraction techniques to study the quality of the CdZnTe crystals grown by Bridgman Technique. Crystallinity and defects within two different growth set-ups, i.e. with and without choked seeding, were compared by imaging the crystal orientation topography with white beam X-ray diffraction topography (WBXDT). The X-ray diffraction topography results show high correlation with large-area infrared transmission images of the crystals. Grain boundaries that are highly decorated with Te inclusions are observed. Characteristic Te inclusion arrangements as a result of growth conditions are discussed. We also measured the electronic properties of the detectors fabricated from ingots grown using two Bridgman processes, and observed a reduction in electrical resistivity of choked-seeding-grown CdZnTe crystals. Our results show that although choked seeding technique holds a promise in the realization of high quality mono-crystalline CdZnTe, current growth parameters must be improved to obtain defect-free crystals. These results are helpful to attain optimal seeding process for Bridgman-growth of large single crystals of CdZnTe.

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