A Novel Deep-Trench Super-Junction SiC MOSFET with Improved Specific On-Resistance.

In this paper, a novel 4H-SiC deep-trench super-junction MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) with a split-gate is proposed and theoretically verified by Sentaurus TCAD simulations. A deep trench filled with P-poly-Si combined with the P-SiC region leads to a charge balance effect. Instead of a full-SiC P region in conventional super-junction MOSFET, this new structure reduces the P region in a super-junction MOSFET, thus helping to lower the specific on-resistance. As a result, the figure of merit (FoM, BV2/Ron,sp) of the proposed new structure is 642% and 39.65% higher than the C-MOS and the SJ-MOS, respectively.

Effects of cavitation erosion-induced surface damage on the corrosion behaviour of TA31 Ti alloy.

This study used electrochemical noise technology to analyse the effects of surface damage induced by cavitation erosion (CE) on the pitting and passivation behaviours of TA31 Ti alloy. According to the results, TA31 Ti alloy exhibited high corrosion resistance in NaCl solutions. However, the residual tensile stress layer generated during grinding and polishing reduced its passivation ability. Subsequently, the residual tensile stress layer was eliminated after CE for 1 h, improving the passivation ability of the material. Thereafter, pitting corrosion was initiated on the material surface. Increasing the CE time from 1 h to 2 h gradually decreased the passivation ability of the alloy. A large number of CE holes promoted the transition from pitting initiation to metastable pitting growth. which gradually dominated the surface of TA31 Ti alloy. The damage mechanism of uniform thinning increased the passivation ability and stability of the alloy with the increase in CE time from 2 h to 6 h. Therefore, the surface of TA31 Ti alloy was dominated by the initiation of pitting corrosion.

Simulation Studies on Single-Event Effects and the Mechanisms of SiC VDMOS from a Structural Perspective.

The single-event effect reliability issue is one of the most critical concerns in the context of space applications for SiC VDMOS. In this paper, the SEE characteristics and mechanisms of the proposed deep trench gate superjunction (DTSJ), conventional trench gate superjunction (CTSJ), conventional trench gate (CT), and conventional planar gate (CT) SiC VDMOS are comprehensively analyzed and simulated. Extensive simulations demonstrate the maximum SET current peaks of DTSJ-, CTSJ-, CT-, and CP SiC VDMOS, which are 188 mA, 218 mA, 242 mA, and 255 mA, with a bias voltage VDS of 300 V and LET = 120 MeV·cm2/mg, respectively. The total charges of DTSJ-, CTSJ-, CT-, and CP SiC VDMOS collected at the drain are 320 pC, 1100 pC, 885 pC, and 567 pC, respectively. A definition and calculation of the charge enhancement factor (CEF) are proposed. The CEF values of DTSJ-, CTSJ-, CT-, and CP SiC VDMOS are 43, 160, 117, and 55, respectively. Compared with CTSJ-, CT-, and CP SiC VDMOS, the total charge and CEF of the DTSJ SiC VDMOS are reduced by 70.9%, 62.4%, 43.6% and 73.1%, 63.2%, and 21.8%, respectively. The maximum SET lattice temperature of the DTSJ SiC VDMOS is less than 2823 K under the wide operating conditions of a drain bias voltage VDS ranging from 100 V to 1100 V and a LET value ranging from 1 MeV·cm2/mg to 120 MeV·cm2/mg, while the maximum SET lattice temperatures of the other three SiC VDMOS significantly exceed 3100 K. The SEGR LET thresholds of DTSJ-, CTSJ-, CT-, and CP SiC VDMOS are approximately 100 MeV·cm2/mg, 15 MeV·cm2/mg, 15 MeV·cm2/mg, and 60 MeV·cm2/mg, respectively, while the value of VDS = 1100 V.

Comparing a novel Catfish flow restoration device and the Solitaire stent retriever for thrombectomy revascularisation in emergent largevessel occlusion stroke: a prospective randomised controlled study.

BACKGROUND: The Catfish stent retriever is a newly developed mechanical thrombectomy device for rapid recanalisation in emergent large vessel occlusion (ELVO) stroke. The current trial aimed to assess whether the Catfish stent retriever is non-inferior to the Solitaire stent retriever in terms of outcomes in ELVO stroke. METHODS: This was a randomised, prospective, parallel-group, multicentre, open-label, non-inferiority study conducted at 18 sites in China. The primary outcome was the proportion of cases with successful recanalisation (modified thrombolysis in cerebral infarction score of 2b or 3) following the procedure. Secondary efficacy outcomes included the National Institutes of Health Stroke Scale scores at 24 hours and 7 days or discharge if earlier, time from artery puncture to successful recanalisation and good clinical outcome (modified Rankin scale score ≤2) at 90 days. Safety outcomes included symptomatic intracranial haemorrhage, all cause-death and severe adverse events at 90 days. RESULTS: Between 3 March 2019 and 5 June 2021, 118 and 120 patients were randomly allocated to the Catfish and Solitaire groups, respectively. The primary endpoint after all endovascular procedures was non-inferior in the Catfish group (88.5%, 100/113) than in the Solitaire group (87.7%, 100/114), with a rate difference (RD) of 0.78% (95% CI -7.64 to -9.20; p=0.001). Sensitivity analysis only considering the per-protocol set also yielded similar results, with an RD of 0.83% (95% CI -7.03 to -8.70; p<0.001). Additionally, the proportions of cases with good clinical outcomes (47.8% vs 50.0%, p=0.739) and all-cause death rates (17.7% vs 18.8%, p=0.700) were similar in both groups at 90 days. CONCLUSIONS: The Catfish stent retriever is an effective and safe device for endovascular recanalisation in ELVO stroke. TRIAL REGISTRATION NUMBER: NCT03820882.

Understanding the Corrosion Behavior of Nickel-Aluminum Bronze Induced by Cavitation Corrosion Using Electrochemical Noise: Selective Phase Corrosion and Uniform Corrosion.

Nickel-aluminum bronze (NAB) is widely used to fabricate flow-handling components because of its good cavitation corrosion (CE) resistance and superior casting property. The existence of different phases, e.g., the α phase, ß phase and κ phase, can cause significant selective phase corrosion on NAB. However, under the action of CE with different times, the influence of these phases on the corrosion behavior of NAB, including selective phase corrosion and uniform corrosion, needs to be further studied, which can contribute to a deep understanding of the CE mechanism of NAB in corrosive media. In this work, the corrosion behavior of NAB in 3.5 wt.% NaCl solution after different CE times was evaluated by electrochemical noise (EN), combined with scanning Kelvin probe force microscopy (SKPFM) and morphology analysis. The results showed that the corrosion behavior of NAB was closely associated with the variation in its complex microstructure after different CE times. Selective phase corrosion played a crucial role in the surface damage before 0.5 h of CE. With the prolongation of CE time, the stripping of κ phases decreased the degree of selective phase corrosion of NAB. As a result, both selective phase corrosion and uniform corrosion presented equal performances after 1 h of CE. However, after CE for 2-5 h, uniform corrosion had a dominant impact on the surface damage of NAB. Eventually, the corrosion mechanism of NAB after different CE times was clarified based on the relevant experimental results.