17 research outputs found
High Energy Hadrons Fluence Measurements in the LHC during 2015, 2016 and 2017 Proton Physics Operations.
In order to reduce the risk of failure for the electronic equipment installed in the underground areas of LHC, every year the Radiation Monitors (RadMons) are used to measure the High Energy Hadrons (HEH) fluence in the tunnel and in the shielded areas. In the framework of the Radiation to Electronics Project (R2E), this work discusses the measurements for the proton physics operations in 2015, 2016 and 2017
Single-Event Radiation Effects in Silicon Carbide Power MOSFETs
In this research, the radiation induced single event effects (SEE) observed in silicon
carbide (SiC) power MOSFETs have been studied. Heavy ions, terrestrial neutrons and
protons were selected as radiation environments to be investigated, as representative of
space, avionics and high-energy accelerator applications. SEE tests and electrical analysis
were performed in order to identify the modes and mechanisms of failure, and to assess
the reliability of commercial SiC MOSFET technologies. The research initially focused on
the non-catastrophic SEEs induced by heavy-ion irradiation, which represent a significant
risk for the part reliability in space applications. The broad-beam and microbeam results
pave the way to the understanding of the degradation mechanism, named single event
leakage current (SELC). Two types of degradation are described in this work, involving
different parts of the SiC MOSFET structure depending on the applied voltage during the
operation. At low bias the SELC is observed in the region under the gate oxide, whereas
for voltages over a certain threshold a second mechanism involving the p-n junction is
newly added. Heavy-ion latent damage effects were also studied through radiation tests
and scanning electron microscopy (SEM) analysis of the damaged site. Two mechanisms
were observed, involving the gate oxide and the SiC crystal lattice. Finally, the heavy-ion
SEEs are summarised as function of the operational bias and linear energy transfer
(LET). The second part of this work focused on SiC MOSFET reliability when exposed to
proton and terrestrial-neutron environments. Accelerated single event burnout tests were
performed using devices with different architectures. Electrical analysis of the damaged
devices was carried out to investigate the failure mechanism. The results provide useful
information about the reliability of the commercial SiC MOSFET technologies for avionic
and high-energy accelerator applications.
This project was carried out in the framework of a collaboration between the Physics
Department at the University of Jyväskylä, the radiation to electronics (R2E) project at the
European Council for Nuclear Research (CERN), and the Advanced Power Semiconductor
(APS) Laboratory at ETH Zürich.
Keywords: silicon carbide, power MOSFETs, radiation effects, Single Event Effects,
SELC, SEB, SEGR, latent damageTässä työssä on tutkittu yksittäisten hiukkasten aiheuttamia säteilyilmiöitä piikarbidista
(SiC) valmistetuissa MOSFET-tehotransistoreissa. Tutkimukseen valitut säteilytyypit
sisälsivät raskaita hiukkasia, neutroneja sekä protoneja. Näitä hiukkasia tavataan tyypillisesti
avaruus-, ilmailu- sekä kiihdytinsovelluksien toimintaympäristöissä. Säteilytestaukset
ja sähköiset karakterisoinnit suoritettiin, jotta vauriomekanismien eri moodit saatiin
selville, sekä kaupallisten SiC MOSFET-teknologioiden luotettavuus arvioitua. Ensisijaisesti
tutkimus keskittyi raskaiden hiukkasten ei-katastrofaalisiin säteilyilmiöihin, jotka
luovat merkittävän riskin komponenttien luotettavuudelle ja sen arvioimiselle avaruussovelluksissa.
Fokusoituja (ns. mikrosuihkuja) sekä laaja-alaisia suihkuja käyttämällä on
mahdollista paremmin ymmärtää SELC-vauriomekanismia (engl. Single Event Leakage
Current). Tässä työssä kuvataan kahdenlaista SELC-vauriotyyppiä, mitkä kohdistuvat
fyysisesti transistorin eri osiin riippuen käytetystä biasjännitteestä. Matalammilla
jännitteillä SELC havaitaan hilaoksidin alueella, kun taas korkeammilla jännitteillä
vaurio havaitaan transistorin runkodiodin alueella. Työssä tutkittiin myös raskaiden
hiukkasten aiheuttamia piileviä (latentteja) vaurioita kuvantamalla vauriokohtia elektronimikroskoopin
avulla. Latentteja vauriotyyppejäkin havaitaan kahdenlaisia, joihin
liittyvät alueet komponentin sisällä ovat hilaoksidi sekä SiC substraatti. Yllä mainituista
tuloksista on mahdollista määrittää raskaiden hiukkasten SEE-ilmiöiden eri alueet käyttöjännitteen
sekä hiukkasen energiajätön funktiona. Työn toisessa osassa keskityttiin SiC
MOSFETien luotettavuuteen protoni- ja neutronisäteily-ympäristöissa. Kiihdytettyjä
SEB-testejä (engl. Single Event Burnout) käyttäen eri komponenttiarkkitehtuureja tutkittiin.
Saadut tulokset antavat hyödyllistä tietoa kaupallisten SiC MOSFET teknologioiden
luotettavuudesta ilmailu- sekä kiihdytinsovelluksissa.
Tämä projekti tehtiin yhteistyössä Jyväskylän yliopiston fysiikan laitoksen, CERN:n
R2E-projektin (Radiation to Electronics), sekä ETH Zürichin APS (Advanced Power
Semiconductor) laboratorion kanssa.
Avainsanat: piikarbidi, teho-MOSFET, säteilynvaikutukset, SEE, SELC, SEB, SEGR,
latentit vaurio
Heavy-Ion-Induced Defects in Degraded SiC Power MOSFETs
Cathodoluminescence spectroscopy is used to investigate the formation of point- and extended defects in SiC power MOSFETs exposed to heavy-ions. Devices showing single event leakage current (SELC) effects are analysed and compared to pristine samples. Common luminescence peaks of defect centers localized in the thermal-SiO2 are identified, together with peaks at the characteristic wavelength of extended defects.peerReviewe
TID, ΦHEH and ΦThN measurements along the SPS accelerator and the adjacent Tunnel Access Areas
In this document, the measurements of Total Ionizing Dose, High Energy Hadron fluence and Thermal Neutron fluence are presented for some areas of the Super Proton Synchrotron, cumulated during 2017 and 2018. The investigation aims at characterizing the radiation field that might affect some sensitive equipment installed by the Beam Instrumentation group (BE/BI). The areas investigated are the arcs and tunnel access areas TA1, TA2 and TA6
Investigation of Electrically Active Defects in SiC Power Diodes Caused by Heavy Ion Irradiation
Deep-level transient spectroscopy (DLTS) and minority carrier transient spectroscopy (MCTS) are used to investigate electrically active defects in commercial silicon carbide (SiC) Schottky power diodes after heavy-ion microbeam irradiation at different voltages. The DLTS and MCTS spectra of pristine samples are analyzed and compared to devices showing or not signatures of single event leakage current (SELC) degradation. An additional peak labeled 'C' with an activation energy of 0.17 eV below the conduction band edge is observed in the DLTS spectra of a sample degraded with SELC.ISSN:0018-9499ISSN:1558-157
High-Energy Proton and Atmospheric-Neutron Irradiations of SiC Power MOSFETs: SEB Study and Impact on Channel and Drift Resistances
Accelerated single event burnout (SEB) tests with 200 MeV protons and atmospheric neutrons were performed for commercial silicon carbide (SiC) power MOSFETs with different architectures (i.e., planar gate, asymmetric trench, and symmetric trench). The average electric fields over the depletion layer width and the electric field distributions are reported for the tested conditions and compared for the three architectures, confirming the necessity of a lower de-rating for the trench design to protect from SEB, compared to planar ones. In addition to the epitaxial layer design, the influence of other design parameters on the SEB threshold is discussed. Finally, to investigate the presence of precursor damage in the pre-SEB region, a methodology is presented and used to study the radiation-induced degradation of the channel and drift resistances of devices that survived the SEB tests.ISSN:0018-9499ISSN:1558-157
Radiation Levels at the LHC: 2012, 2015 and 2016 Proton Physics Operations in View of HL-LHC requirements
The variety of beam losses produced in the Large Hadron Collider (LHC) creates a mixed and complex radiation field. During 2012, 2015 and 2016, Beam Loss Monitors and RadMons were used to monitor the inte-grated dose and the High Energy Hadrons fluence in order to anticipate the electronics degradation and inves-tigate the cause of failures. The annual radiation levels are compared; highlighting the mechanisms in the pro-duction of beam losses and the impact of the different squeeze and crossing angle. In addition, the increase of beam-gas interaction is discussed comparing operations at 25 ns and 50 ns bunch spacing. A strategy is presented to allow for a continuous respective evaluation during the upcoming LHC and future High Luminosity LHC (HL-LHC) operations
Current Transport Mechanism for Heavy-Ion Degraded SiC MOSFETs
High sensitivity of SiC power MOSFETs has been
observed under heavy ion irradiation, leading to permanent
increase of drain and gate leakage currents. Electrical postirradiation analysis confirmed the degradation of the gate oxide
and the blocking capability of the devices. At low drain bias, the
leakage path forms between drain and gate, while at higher bias
the heavy ion induced leakage path is mostly from drain to source.
An electrical model is proposed to explain the current transport
mechanism for heavy-ion degraded SiC power MOSFETs.peerReviewe
Current Transport Mechanism for Heavy-Ion Degraded SiC MOSFETs
ISSN:0018-9499ISSN:1558-157
Isotopic Enriched and Natural SiC Junction Barrier Schottky Diodes under Heavy Ion Irradiation.
The radiation tolerance of isotopic enriched and natural silicon carbide junction barrier Schottky diodes are compared under heavy ion irradiation. Both types of devices experience leakage current degradation as well as single event burnout events. The results were comparable, although the data may indicate a marginally lower thresholds for the isotopic enriched devices at lower LET. Slightly higher reverse bias threshold values for leakage current degradation was also observed compared to previously published work.peerReviewe