High Voltage SiC Schottky Diodes in Rectifiers for X-Ray Generators

Silicon-Carbide-based semiconductors offer realization of efficient high voltage components, with high switching speed and low conduction losses. SiC Schottky diodes with safe blocking capability of at least 4 kV were produced and characterized. A simulation model for loss determination was developed. Real losses were determined on a small scale test setup and chip temperature distribution was obtained from that, combined with FEM calculation. A full-size rectifier 100 kW/140 kV-SiC-rectifier module with six times higher power density than with conventional Si-technology was realized.

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Effects of Very High Workfunction Metals or Metal Alloys (NiCr) on High Switching Speed, HV Schottky Diodes for Mixed Signal or RF ASIC

MRS Advances ◽

10.1557/adv.2020.336 ◽

2020 ◽

Vol 5 (37-38) ◽

pp. 1937-1946

Author(s):

J. Pan ◽

A. Gaibrois ◽

M. Marripelly ◽

J. Leung ◽

S. Suko ◽

...

Keyword(s):

Work Function ◽

Schottky Diodes ◽

Thermionic Emission ◽

Metal Alloys ◽

Forward Voltage ◽

Switching Speed ◽

External Bias ◽

High Switching Speed ◽

High Work ◽

Very High

AbstractFor high switching speed HV Schottky diodes, with very high work function metal and extremely lightly doped epi, the built-in potential may be too high for thermionic emission to occur, when the applied external voltage is quite low (near VF = 0.07V). If the epi is lightly doped p type, the built-in potential (VBuilt-in: potential difference between the metal and silicon Fermi levels) is 1.0V (measured with CV). If the external bias is 0.1V, near the measured VF, it is not enough to overcome the built-in potential for thermionic emission as illustrated. It is likely that in addition to thermionic emission, tunnelling and diffusion currents also contribute to the total HV Schottky diode forward current. TCAD simulation of HV Schottky diodes with N+ guard bands suggests the potential barrier and electric fields at the Schottky junction are relatively high for thermionic emission to occur, when external bias V ≈ VF. In this paper we report HV Schottky diodes fabricated with various metals, metal alloys and epitaxial films. Metal work functions and epi doping profiles are extracted with high frequency Capacitance-Voltage (CV) technique. 150V of breakdown voltage and very low forward voltage (VF = 0.07V) are demonstrated. The measured data indicate very high work function metal or metal alloy is needed to achieve high switching speed and low forward voltage.

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Next Generation Planar 1700 V, 20 mΩ 4H-SiC DMOSFETs with Low Specific On-Resistance and High Switching Speed

Materials Science Forum ◽

10.4028/www.scientific.net/msf.897.521 ◽

2017 ◽

Vol 897 ◽

pp. 521-524 ◽

Cited By ~ 5

Author(s):

Q.J. Zhang ◽

G. Wang ◽

Charlotte Jonas ◽

Craig Capell ◽

Steve Pickle ◽

...

Keyword(s):

Detailed Analysis ◽

High Voltage ◽

Dynamic Characteristics ◽

High Power ◽

Switching Speed ◽

Static And Dynamic Characteristics ◽

Medium Voltage ◽

Fast Switching ◽

High Switching Speed ◽

Fast Switching Speed

Due to their fast switching speed, knee-free forward characteristics, and a robust, low reverse recovery body diode, SiC MOSFETs are ideal candidates to replace silicon IGBTs in many high-power medium-voltage applications. 1700 V SiC MOSFETs have already been released to production at Wolfspeed based on its 2nd Gen technology. In this paper, we present our latest results in high voltage 4H-SiC MOSFET development. A low specific on-resistance of 4.7 mΩ⋅cm2 has been achieved on 1700 V, 20 mΩ 4H-SiC DMOSFETs at 250°C based on a 3rd generation planar MOSFET platform, which is less than half of the resistance of the previous generation devices. A detailed analysis has been carried out with respect to the static and dynamic characteristics, third quadrant conduction, and body diode reverse recovery charge, etc.

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High-voltage cable plug and socket connections for medical X-ray equipment

10.3403/03221195 ◽

2005 ◽

Keyword(s):

High Voltage ◽

X Ray

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Study of Multiaspect and Multistatic Sonar Systems Using a Small-Scale Test Bed

10.21236/ada542185 ◽

2010 ◽

Author(s):

Jon La Follett ◽

John Stroud ◽

Pat Malvoso ◽

Joseph Lopes ◽

Raymond Lim ◽

...

Keyword(s):

Small Scale ◽

Test Bed ◽

Sonar Systems ◽

Scale Test

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Time-frequency analysis of VHF wave form for precise location of partial discharge in small-scale high voltage apparatuses

Proceedings of the 7th International Conference on Properties and Applications of Dielectric Materials (Cat. No.03CH37417) ◽

10.1109/icpadm.2003.1218422 ◽

2004 ◽

Author(s):

C.K. Lee ◽

Y. Muramoto ◽

N. Hozumi ◽

M. Nagao

Keyword(s):

Frequency Analysis ◽

High Voltage ◽

Partial Discharge ◽

Small Scale ◽

Wave Form ◽

Precise Location ◽

Time Frequency Analysis ◽

Time Frequency

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QPOs in compact binaries from small scale eruptions in an inner magnetized disk

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3410 ◽

2020 ◽

Author(s):

Nicolas Scepi ◽

Mitchell C Begelman ◽

Jason Dexter

Keyword(s):

Rapid Heating ◽

Small Scale ◽

Type B ◽

Periodic Oscillations ◽

X Ray ◽

Compact Binaries ◽

Heating And Cooling ◽

Low Mass ◽

X Ray Binaries ◽

Standard Disk

Abstract Dwarf novæ (DNe) and low mass X-ray binaries (LMXBs) are compact binaries showing variability on time scales from years to less than seconds. Here, we focus on explaining part of the rapid fluctuations in DNe, following the framework of recent studies on the monthly eruptions of DNe that use a hybrid disk composed of an outer standard disk and an inner magnetized disk. We show that the ionization instability, that is responsible for the monthly eruptions of DNe, is also able to operate in the inner magnetized disk. Given the low density and the fast accretion time scale of the inner magnetized disk, the ionization instability generates small, rapid heating and cooling fronts propagating back and forth in the inner disk. This leads to quasi-periodic oscillations (QPOs) with a period of the order of 1000 s. A strong prediction of our model is that these QPOs can only develop in quiescence or at the beginning/end of an outburst. We propose that these rapid fluctuations might explain a subclass of already observed QPOs in DNe as well as a, still to observe, subclass of QPOs in LMXBs. We also extrapolate to the possibility that the radiation pressure instability might be related to Type B QPOs in LMXBs.

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Non-Invasive Technical Investigation of English Portrait Miniatures Attributed to Nicholas Hilliard and Isaac Oliver

Heritage ◽

10.3390/heritage4030064 ◽

2021 ◽

Vol 4 (3) ◽

pp. 1165-1181

Author(s):

Flavia Fiorillo ◽

Lucia Burgio ◽

Christine Slottved Kimbriel ◽

Paola Ricciardi

Keyword(s):

Fluorescence Spectroscopy ◽

Scientific Methodology ◽

Small Scale ◽

Artistic Practice ◽

X Ray ◽

Non Invasive ◽

Miniature Painting ◽

Entire Career ◽

Similarities And Differences ◽

Victoria And Albert Museum

This study presents the results of the technical investigation carried out on several English portrait miniatures painted in the 16th and 17th century by Nicholas Hilliard and Isaac Oliver, two of the most famous limners working at the Tudor and Stuart courts. The 23 objects chosen for the analysis, spanning almost the entire career of the two artists, belong to the collections of the Victoria and Albert Museum (London) and the Fitzwilliam Museum (Cambridge). A non-invasive scientific methodology, comprising of stereo and optical microscopies, Raman microscopy, and X-ray fluorescence spectroscopy, was required for the investigation of these small-scale and fragile objects. The palettes and working techniques of the two artists were characterised, focusing in particular on the examination of flesh tones, mouths, and eyes. These findings were also compared to the information written in the treatises on miniature painting circulating during the artists’ lifetime. By identifying the materials and techniques most widely employed by the two artists, this study provides information about similarities and differences in their working methods, which can help to understand their artistic practice as well as contribute to matters of attribution.

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