The novel SiC/Si heterojunction power MOSFET has been advanced to improve the tradeoff between the breakdown voltage (BV) and specific on-resistance (<inline-formula> <tex-math notation="LaTeX">{R}_{ ...\mathrm{ON},\textsf {sp}} </tex-math></inline-formula>). The innovative terminal technology of breakdown point transfer has been applied to SiC/Si MOSFET, which transfers the breakdown point from the high electric field points to the low electric field areas and improves the BV compared with the conventional Si power MOSFET. The results have been shown by technology computer aided design simulation that the BV has been improved for SiC/Si U-MOSFET due to PBT technology. The BV of the proposed SiC/Si U-MOSFET is increased to 358 V compared with the Si U-MOSFET of 107 V with the same device parameters. The simulated <inline-formula> <tex-math notation="LaTeX">{R}_{ \mathrm{ON},\textsf {sp}} </tex-math></inline-formula> of the SiC/Si U-MOSFET is <inline-formula> <tex-math notation="LaTeX">0.51~\textsf {m}\Omega \cdot \textsf {cm}^{2} </tex-math></inline-formula> with the BV of 358 V, which is lower than that of <inline-formula> <tex-math notation="LaTeX">1.12~\textsf {m}\Omega \cdot \textsf {cm}^{2} </tex-math></inline-formula> with the BV of 107 V for the conventional Si U-MOSFET. The important law is discovered that the high BV and low <inline-formula> <tex-math notation="LaTeX">{R}_{ \mathrm{ON},\textsf {sp}} </tex-math></inline-formula> can be obtained simultaneously for SiC/Si U-MOSFET when the depth of the trench oxide layer is increased, which cannot be taken into account in the conventional Si U-MOSFET. Therefore, the silicon and superjunction VDMOS (double-diffused MOSFET) limits had been broken for SiC/Si U-MOSFET. The influences of the different interface charge (acceptorlike and donorlike) have been analyzed for SiC/Si VDMOS and SiC/Si U-MOSFET.
In this letter, we report on demonstrating a high performance vertical β-Ga 2 O 3 Schottky barrier diode (SBD) based on a self-aligned beveled fluorine plasma treatment (BFPT) edge termination ...structure. Owing to the strong electronegativity of fluorine ions, the fixed negative charges introduced by F ions during self-aligned BFPT process alleviate the electric field crowding, reduce the reverse leakage current and improve the breakdown voltage up to 1 050V even with a low differential on resistance of 2.5 mΩ·cm 2 , combining with a high Ion/Ioff of 109, a Schottky barrier height of 1.03 eV and a low ideality factor of 1.07-1.11.Without implantation and post annealing, the self-aligned BFPT can serve as a simple, effective and viable edge termination technique to fabricate high performance β-Ga 2 O 3 rectifiers.
The time formative time lag (t f ) in the breakdown process of polymers on a nanosecond time scale is calculated. By reviewing the mechanisms related to breakdown of solid dielectrics, it is ...concluded that the avalanche breakdown mechanism is mainly responsible for the breakdown phenomenon of polymers on a nanosecond time scale, which is similar to the Townsend theory of gas breakdown under short pulses. In addition, the maximum functioning time of this theory is ascertained as 1 μs. When the time is longer than 1 μs, the thermal breakdown mechanism and other mechanisms begin to play the role. A formula to calculate t f for the avalanche breakdown mechanism is presented. This formula takes into account different factors that have an influence on t f , such as the dielectric size, type and purity. With this formula, it is calculated that t f for common polymers with a thickness ranging from 0.001-1 mm is about 0.01-100 ns. Experimental results in literatures were summarized to support the calculation results. The formative time lag is a key parameter to evaluate the pulse width effect on the electric breakdown strength on a nanosecond time scale.
High voltage insulation properties of HFO1234ze Koch, M.; Franck, C. M.
IEEE transactions on dielectrics and electrical insulation,
2015-December, 2015-12-00, 20151201, Letnik:
22, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Recently it was shown that it is possible to predict the breakdown voltages of arbitrary electrode configurations under standard voltage applications for electron attaching gases with a stepped ...leader model originally proposed for SF6. In this contribution this model was applied to the hydrofluoroolefin HFO1234ze. The parameters, which are necessary for the modeling, are derived from measurement of statistical and formative time lags in an electrode configuration with a homogeneous background field with a small protrusion. The parameters are used to predict the breakdown voltage for technical relevant geometries and standard voltage wave shapes. To verify these predictions, breakdown experiments in nearly homogeneous and strongly inhomogeneous field configurations with AC and lightning impulse voltage application of both polarities were performed. The hydrofluoroolefin exhibits insulation properties which are quite similar to those of SF6. Therefore it could be considered as admixture for high voltage gaseous insulations or as replacement in medium voltage equipment. For applications using the pure gas the temperature and pressure range has to be limited to prevent liquefaction. The good match between the simulations and the experiments gives evidence that the model can be applied to a broad range of other novel electron attaching gases as well.
Continuous memory technology scaling causes memory cells to be vulnerable to wearout. To ensure reliable operations of circuits and systems in the presence of wearout, we require accurate estimation ...of the lifetime of circuits and systems degraded by wearout. Since the conventional method of estimating circuit and system reliability degradation based on device-level accelerated life test (ALT) does not account for the tolerance of a circuit and a system to a wearout failure of a device, accelerated lifetime testing at the circuit and system level is necessary. For accurate estimation of system reliability using system-level ALT, we propose a method that optimizes the design of experiments for ALT. From significant observations from failure data statistics of system-level ALT with various stress conditions applied to the memory system of the Leon3 as a case study, we define acceptability regions for memory testing of each wearout mechanism. In addition, by analyzing errors in estimating Weibull parameters from system-level ALT, we develop a methodology that optimizes experimental designs in acceptability regions of each wearout mechanism to minimize such estimation errors in system-level ALT.
By describing the gas breakdown phenomenon from the view of probability density function (pdf) estimation, a numerical calculation model is proposed to apply for the design of a 1 <inline-formula> ...<tex-math notation="LaTeX">+</tex-math> </inline-formula> n-type multistage gas spark switch (GSS). The physical principle, numerical calculation model, design procedures, and experimental test for GSS are hence described in considerable detail in the text. Various key operating parameters for GSS, that is, nontrigger rate <inline-formula> <tex-math notation="LaTeX">\xi </tex-math> </inline-formula>, error breakdown rate <inline-formula> <tex-math notation="LaTeX">\chi </tex-math> </inline-formula>, mean breakdown voltage, and breakdown voltage jitter <inline-formula> <tex-math notation="LaTeX">\sigma </tex-math> </inline-formula>, are deduced from the calculation model. Optimization of operation parameters helps to design reliable compact GSS for pulsed power systems. The validity of the calculation model is verified and its suitability to a more general switch design is discussed.
In view of the contemporary scenario and importance of alternative liquid dielectrics, IEEE DEIS Technical Committee on Liquid Dielectrics laid emphasis on pre-breakdown phenomena of ester dielectric ...fluids. The present article reports the background knowledge on the breakdown theories and behavior of streamers in insulating oils. The major influencing properties of the streamers aroused in liquid insulating systems are discussed keeping in view of the ester based dielectric fluids. Importantly, modelling of streamers, testing approaches, and review of pre-breakdown phenomena in ester dielectric fluids has been presented.
High-voltage thin film transistors (HVTFTs) have potential applications for driving high-voltage devices. Drain offset is a typical HVTFT structure but degrades ON-current. In this study, a-IGZO ...split-channel dual-gate HVTFTs are explored to achieve both high-voltage and high breakdown voltage. It is found that the dual-gate structure without split-channel improves the ON-current of offset-drain thin film transistors (TFTs) but degrades the breakdown voltage. Experiment results show that high ON-current induced thermal breakdown is the main reason limiting the breakdown voltage of dual-gate HVTFTs. The split-channel structure is introduced to enhance the heat dissipation and thus dual-gate HVTFTs with higher breakdown voltage were obtained. Split-channel dual-gate HVTFTs were fabricated with a breakdown voltage of 464 V, ON-current of <inline-formula> <tex-math notation="LaTeX">61.60~\mu \text{A} </tex-math></inline-formula>, threshold voltage of −1.0 V, and subthreshold swing of 0.38 V/dec. This study demonstrates that split-channel dual-gate HVTFTs are a promising candidate for high-voltage and high ON-current TFT.
The focus of this paper is on the effectiveness of lightning impulse (LI) with different parameters for detecting protrusion defects in gas insulated switchgear (GIS). The study examines the 50% (U ...50 ) breakdown probability for typical protrusion defects on the conductor of a 363 kV class GIS. A quantitative method is developed to predict breakdown voltage, calculate minimum detectable length of defect, and express the effectiveness of the LI test. The results show that there is little difference of U 50 between aperiodic and oscillating LI. Corresponding detecting effectiveness decreases for LI with long wavefront, which is expressed quantitatively by detectable area. The critical defect length detected increases with increased wavefront. This study provides a general method to express the effectiveness of LI with different parameters for detecting protrusion defects and it support the LI test for on-site testing of GIS.
Space charge accumulation inside the cross-linked polyethylene (XLPE) insulation is one of the most serious problems in HVDC cable operation. In this paper, the voltage stabilizers that have ...excellent compatibility with XLPE are used to suppress the space charge in XLPE insulation. Three different voltage stabilizers, 4,4'-Difluorobenzophenone, 4,4'-Dihydroxybenzophenone, and 4,4'-Bis (dimethyl amino) benzyl, denoted as A, B, and C, respectively, were added into XLPE material with additive content of 0.5 wt%, and neat XLPE was used as a control. The differential scanning calorimeter (DSC) test, tensile test, DC conductivity and breakdown strength measurements were employed to characterize the thermal, mechanical and electrical properties of the samples respectively. Moreover, the space charge behaviors were investigated using the PEA method, and the trap-controlled carrier mobility was evaluated by the depolarization processes of the space charge. The mechanical and thermal analyses indicate that the presence of voltage stabilizers does not significantly change the microstructure of XLPE, as required for the preparation of HVDC cable insulation. Though the influence of voltage stabilizers on DC conductivity is not obvious, a higher breakdown strength was found in the voltage-stabilizer modified XLPE samples. In addition, XLPE modified by the voltage stabilizers B and C with higher trap-controlled carrier mobility show a good ability to suppress space charge in XLPE insulation, that is, less space charge accumulation and faster space charge dissipation than the neat XLPE. The experimental results reveal that the voltage stabilizers B and C show great promise for use in HVDC cable application.
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