Papers by Keyword: Electrical Breakdown

Abstract: In order to expand the possibilities of practical application of polymeric materials we studied syndiotactic 1,2-polybutadiene (1,2-SPB). The experimental procedure and the MV-002 device for determining the breakdown voltage and electrical breakdown of a polymer are described in detail. Mathematical models of the dependence of the breakdown voltage of the polymer on the frequency and magnitude of the electrical breakdown of the polymer on the thickness of the sample have been built and studied. Regression analysis was used for mathematical data processing. The reliability of the results obtained is proved by the methods of test statistics.

Abstract: Recently, extensive studies have been carried out on developing a high voltage superconducting apparatus as a substitute for the conventional one. superconducting wires used for a high voltage superconducting apparatus can be damaged under high voltage condition due to electrical breakdown and the damaged superconducting wires may result in the degradation of the critical current (Ic) and index number. Therefore, a study on the degradation characteristics of superconducting wires in accordance with the electrical breakdown should be performed. In this paper, the degradation characteristics of second generation high temperature superconducting (2G HTS) wires with respect to electrical breakdown tests are studied. The applied electrical breakdown voltages to 2G HTS wire are AC and lightning impulse (Imp) ; 50, 60 and 70 kV. The electrical breakdown test is successively repeated five times. The Ic and index number of 2G HTS wires were measured. The relationship between electrical characteristics such as the Ic and index number and the electrical breakdown was analyzed.

Abstract: The accuracy of tool setting has a great influence on the machining accuracy of micro structures. In this paper, electric breakdown in micro gap is used for tool setting and the accuracy of this method is ±0.2μm. Experimental studies have been done to prove the feasibility of this method. Experimental results show that the breakdown voltage is about 30V when the gap between the tool and the tool setting probe is 2μm, and tool diameter has little effect on this phenomenon. With the increase of the tool wear the breakdown voltage shows ascendant trend, so this method can be used to monitor tool wear.

Abstract: Nowadays, the piezoelectric materials are widely used in many areas. The piezoelectric materials will undergo an electrical degradation process during working causes the piezoelectricity and resistance of the piezoelectric materials degrade. The existence of the electrical degradation phenomenon severely limits the applications of the piezoelectric products. During the electrical degradation process, electrical breakdown often occurs and this electrical breakdown has been proposed [1, 2] induces the resistance decrease and local phase changing. In this paper, the electrical breakdown induced current transients are detailed investigated. Three types of current transients are presented and the time durations of current transients are suggested not constant and corresponding to the time duration of the local burn-out process, which is caused by the heat released from the electrical breakdown process.

Abstract: In order to get a deep understanding of the effect of internal electrical field on the electrical breakdown properties of contact materials, two kinds of W-Cu and Cr-Cu joints were prepared in a vacuum sintering furnace. The vacuum breakdown tests were respectively performed at the interface of two joints and pure metal ends in an arc extinguishing chamber, and the surface morphologies after electrical breakdown 50 times were characterized by a scanning electron microscopy equipped with an energy dispersive spectroscopy. The results show that the breakdown strength at the interface is much larger than that of pure metal ends, and the breakdown site deviates from the interface. It is suggested that the existence of internal electrical field at the interface of two contact metals changes the electronic structure, and, thus, the electrical breakdown behavior is influenced.

Abstract: In this contribution a classification of recombination active defects in multicrystalline silicon solar cells made from electronic grade (eg) and upgraded metallurgical grade (umg) silicon feedstock is introduced. On a macroscopic scale the classification is performed by using forward and reversed biased electroluminescence imaging (EL / ReBEL) and imaging of sub-band defect luminescence (ELsub). The luminescence behavior due to structural defects already present in the wafer can be divided into two groups based on their recombination and prebreakdown behavior. As a first step towards a more detailed analysis of the cause for these differences, the classification was also performed on microscopic scale. For this ReBEL and ELsub was performed under an optical microscope (µReBEL/µELsub) and EL was replaced by Electron Beam Induced Current (EBIC). The defect types observed on a macroscopic scale could also be observed on a microscopic scale; however, a third defect type had to be introduced. Finally we propose a qualitative model for the different classified types of recombination active defect structures that can explain the observed recombination and prebreakdown behavior.

Abstract: High-voltage (900 V) 4H-SiC Schottky-barrier diodes (SBD) terminated with guard pnjunction were fabricated and investigated. The guard pn-junction was formed by room temperature boron implantation followed by high temperature annealing. Owing to the transient enhanced boron diffusion during anneal, the depth of guard pn-junction is about 1.7 μm, that is approximately 1 μm deeper than the expected average range of 11B ions in 4H-SiC. The maximum reverse voltage of 4H-SiC SBD produced has been found to be limited by the avalanche breakdown in cylindrical portion of planar pn-junction. The value of the breakdown voltage of 910 V is close to theoretical one calculated for the dopant density  = 2.5×1015 cm-3, n-base thickness d = 12.5 μm and junction curvature rj = 1.7 μm. Dynamic (pulse) reverse current-voltage characteristics were measured in the breakdown regime. It was found that dynamic breakdown voltage increases with shortening the pulse duration. Due to homogeneous avalanche breakdown at the edge of the quard pn-junction and high differential resistance in the breakdown regime, the diodes under test are able to withstand, with no degradation, pulse reverse voltage at least 1600 V.

Abstract: Acceleration factors in acceleration life test of thermal oxides grown on 4H-SiC(0001) wafers and influences of dislocations on oxide reliability have been investigated using time-dependent dielectric breakdown measurements. The thermal oxides are formed by dry oxidation at 1200°C followed by annealing in nitrogen atmosphere. Then, post oxidation annealing in wet ambient at 950°C or hydrogen atmosphere at 800°C were carried out for some of the oxides. Aluminum or poly-Si films with thickness of 300 nm were formed as gate electrodes. The temperature dependence of time-to-breakdown (tBD) indicates that activation energy (Ea) values for the Al-gate and Poly-Si-gate thermal oxides are 0.59 eV - 0.79 eV and 0.34 eV - 0.72 eV, respectively. Analyzing the electric field dependence of tBD, it was indicated that the values of electric acceleration parameters (β) are 2.7 cm/MV - 7.0 cm/MV and 5.8 cm/MV - 7.1 cm/MV for the Al-gate and poly-Si-gate thermal oxides, respectively. In addition, the charge-to-breakdown decreases with increase in the density of basal plane dislocation.