On the influence of strong magnetic field on MOS transistors

Hébrard, Luc; Nguyen, D. V.; Vogel, Dorian; Schell, Jean-Baptiste; Po, Chrystelle; Dumas, Norbert; Uhring, Wilfried; Pascal, Joris

doi:10.1109/icecs.2016.7841264

Cited by 7 publications

(15 citation statements)

References 13 publications

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“…Here q is the elementary electric charge, v is the drift velocity of electrons, and the symbol × denotes the vector cross product. Although our first experimental setup was very basic, we were able to show in [8] that the current reduction only depends on the out-of-plane component of the magnetic field, and that, as expected, the tilt angle • depends on the gate to source voltage through the electron mobility reduction with , i.e. with the transverse electric field.…”

Section: Introductionsupporting

confidence: 59%

“…We have recently published a paper showing that under an outof-plane magnetic field of = 7T, i.e. a 7T field perpendicular to the plane of the chip, the current and the transconductance of NMOS transistors exhibiting a high W/L ratio may be reduced by up to 7% [8]. In addition, this current and transconductance reduction is proportional to tan( • ), where is the mobility of electrons in the MOS channel.…”

Section: Introductionmentioning

confidence: 99%

“…As a consequence a 28% reduction of the MOS transconductance is expected under 14 T, which may be very challenging in terms of circuit design. We have also shown that for transistors with a high W/L (small L/W), which is common in circuit design, the current reduction comes from the deflection of the current lines inside the channel due to the Lorentz force (− • × ) acting on the carriers [8]. Here q is the elementary electric charge, v is the drift velocity of electrons, and the symbol × denotes the vector cross product.…”

Section: Introductionmentioning

confidence: 99%

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Modeling the effect of strong magnetic field on n-type MOSFET in strong inversion

Nguyen

Werling

et al. 2018

2018 25th IEEE International Conference on Electronics, Circuits and Systems (ICECS)

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This paper presents an approach to model the effect of magnetic field on the electrical behavior of MOS transistor. It is shown that an out-of-plane magnetic field B induces a reduction of the channel conductivity, and that this reduction is proportional to the square of B and the square of the carrier mobility. Providing an accurate model of the mobility versus the gate to source and drain to source voltages in all working conditions of the transistor, the effect of B on the MOS transistor can be accurately modeled. Experimental data in strong inversion and linear regime are in very good agreement with the proposed model.

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Section: Introductionsupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling the effect of strong magnetic field on n-type MOSFET in strong inversion

Nguyen

Werling

et al. 2018

2018 25th IEEE International Conference on Electronics, Circuits and Systems (ICECS)

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“…The magnetic field is known to affect semiconductor devices as in some conditions it deviates carriers toward the Si/SiO 2 interface, resulting in change of the magnetoresistance of the conduction channel. In our MOSFET measurements, the effect of the magnetic field on detector response was found to be negligible and within the detector reproducibility; this is likely related to the detector operation in the low drain current region at the low onset V th voltage, which makes the channel magnetoresistance and Hall effect negligible …”

Section: Discussionmentioning

confidence: 99%

“…As drawbacks, MOSFETs show a time dependence of the readout (fading), especially for very small doses (<1 cGy), and a relatively short life, that is, maximum cumulated dose. It is also known that the magnetic field affects semiconductor devices as in some conditions it deviates carriers toward the Si/SiO 2 interface, resulting in change of the magnetoresistance of the conduction channel. This effect is known as the Hall effect, as a small electric field is generated as a result of a magnetic field applied perpendicular to the direction of the drain current, resulting in change of the space charge at the MOSFET conduction channel …”

Section: Introductionmentioning

confidence: 99%

MOSFET dosimeter characterization in MR‐guided radiation therapy (MRgRT) Linac

Yadav

Hallil²,

Tewatia

et al. 2019

J Applied Clin Med Phys

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Purpose: With the increasing use of MR-guided radiation therapy (MRgRT), it becomes important to understand and explore accuracy of medical dosimeters in the presence of magnetic field. The purpose of this work is to characterize metal-oxide-semiconductor field-effect transistors (MOSFETs) in MRgRT systems at 0.345 T magnetic field strength.Methods: A MOSFET dosimetry system, developed by Best Medical Canada for invivo patient dosimetry, was used to study various commissioning tests performed on a MRgRT system, MRIdian ® Linac. We characterized the MOSFET dosimeter with different cable lengths by determining its calibration factor, monitor unit linearity, angular dependence, field size dependence, percentage depth dose (PDD) variation, output factor change, and intensity modulated radiation therapy quality assurance (IMRT QA) verification for several plans. MOSFET results were analyzed and compared with commissioning data and Monte Carlo calculations.Results: MOSFET measurements were not found to be affected by the presence of 0.345 T magnetic field. Calibration factors were similar for different cable length dosimeters either placed at the parallel or perpendicular direction to the magnetic field, with variations of less than 2%. The detector showed good linearity (R 2 = 0.999) for 100-600 MUs range. Output factor measurements were consistent with ionization chamber data within 2.2%. MOSFET PDD measurements were found to be within 1% for 1-15 cm depth range in comparison to ionization chamber.MOSFET normalized angular response matched thermoluminescent detector (TLD) response within 5.5%. The IMRT QA verification data for the MRgRT linac showed that the percentage difference between ionization chamber and MOSFET was 0.91%, 2.05%, and 2.63%, respectively for liver, spine, and mediastinum. Conclusion: MOSFET dosimeters are not affected by the 0.345 T magnetic field in MRgRT system. They showed physics parameters and performance comparable to TLD and ionization chamber; thus, they constitute an alternative to TLD for realtime in-vivo dosimetry in MRgRT procedures. Magnetic resonance image-guided radiation therapy (MRgRT) has gained impetus recently. ViewRay ® (ViewRay Inc., Oakwood, OH) is one of the first MRgRT treatment modalities with an onboard MR scanner attached to a teletherapy 60 Co beam. 1 The MRIdian ® Linac system which combines MR imaging and a 6 MV beam is the latest system developed by ViewRay. MRgRT offers many advantages including real-time imaging, accuracy in treatment delivery, higher soft tissue contrast, and no additional imaging dose. 2 Though there are significant advantages of these hybrid treatment systems with onboard MR scanners, these present a unique challenge to dosimetric measurements with some of the conventional radiation detectors, due to possible magnetic field susceptibility. Several dosimeters are used for quality assurance in radiotherapy; these include ionization chambers (IC), thermoluminescent dosimeters (TLD), film, and active dosimeters such as diodes and metal-oxide-semic...

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Quench protection for high-temperature superconductor cables using active control of current distribution

Marchevsky,

Prestemon

2024

Supercond. Sci. Technol.

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Superconducting magnets of future fusion reactors are expected to rely on composite high-temperature superconductor (HTS) cable conductors. In presently used HTS cables, current sharing between components is limited due to poorly defined contact resistances between superconducting tapes or by design. The interplay between contact and termination resistances is the defining factor for power dissipation in these cables and ultimately defines their safe operational margins. However, the current distribution between components along the composite conductor and inside its terminations is a priori unknown, and presently, no means are available to actively tune current flow distribution in real-time to improve margins of quench protection. Also, the lack of ability to electrically probe individual components makes it impossible to identify conductor damage locations within the cable. In this work, we address both problems by introducing active current control of current distribution between components using cryogenically operated metal-oxide-semiconductor-field-effect transistors (MOSFETs). We demonstrate through simulation and experiments how real-time current controls can help to drastically reduce heat dissipation in a developing hot spot in a two-conductor model system and help identify critical current degradation of individual cable components. Prospects of other potential uses of MOSFET devices for improved voltage detection, AC loss-driven active quench protection, and remnant magnetization reduction in HTS magnets are also discussed.

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On the influence of strong magnetic field on MOS transistors

Cited by 7 publications

References 13 publications

Modeling the effect of strong magnetic field on n-type MOSFET in strong inversion

Modeling the effect of strong magnetic field on n-type MOSFET in strong inversion

MOSFET dosimeter characterization in MR‐guided radiation therapy (MRgRT) Linac

Quench protection for high-temperature superconductor cables using active control of current distribution

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