• Title/Summary/Keyword: Breakdown Mechanism

Search Result 200, Processing Time 0.021 seconds

The microstructure and conduction mechanism of the nonlinear ZnO varistor with $Al_2O_3$ additions ($Al_2O_3$가 미량 첨가된 비선형성 ZnO 바리스터의 미세구조와 전도기구)

  • 한세원;강형부;김형식
    • Electrical & Electronic Materials
    • /
    • v.9 no.7
    • /
    • pp.708-718
    • /
    • 1996
  • The microstructure and electrical properties of the nonlinear ZnO varistor with A1$_{2}$ $O_{3}$ additions is investigated. The variation of nonlinear behavior with A1$_{2}$ $O_{3}$ additions is indicated from J-E and C-V measurement to be a result of the change of the interface defects density $N_{t}$ at the grain boundaries and the donor concentration $N_{d}$ in the ZnO grains. The optimum composition which has the nonlinear coefficients of -57 was observed in the sample with 0.005wt% A1$_{2}$ $O_{3}$ additions. The conduction mechanism at the pre-breakdown region is consistent with a Schottky thermal emission process obeying a relation given by $J^{\var}$exp[-(.psi.-.betha. $E^{1}$2/)kT] and the conduction process at the breakdown region follows a Fowler-Nordheim tunneling mechanism of the form $J^{\var}$exp(-.gamma./E).

  • PDF

Improving Lifetime Prediction Modeling for SiON Dielectric nMOSFETs with Time-Dependent Dielectric Breakdown Degradation (SiON 절연층 nMOSFET의 Time Dependent Dielectric Breakdown 열화 수명 예측 모델링 개선)

  • Yeohyeok Yun
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
    • /
    • v.16 no.4
    • /
    • pp.173-179
    • /
    • 2023
  • This paper analyzes the time-dependent dielectric breakdown(TDDB) degradation mechanism for each stress region of Peri devices manufactured by 4th generation VNAND process, and presents a complementary lifetime prediction model that improves speed and accuracy in a wider reliability evaluation region compared to the conventional model presented. SiON dielectric nMOSFETs were measured 10 times each under 5 constant voltage stress(CVS) conditions. The analysis of stress-induced leakage current(SILC) confirmed the significance of the field-based degradation mechanism in the low electric field region and the current-based degradation mechanism in the high field region. Time-to-failure(TF) was extracted from Weibull distribution to ascertain the lifetime prediction limitations of the conventional E-model and 1/E-model, and a parallel complementary model including both electric field and current based degradation mechanisms was proposed by extracting and combining the thermal bond breakage rate constant(k) of each model. Finally, when predicting the lifetime of the measured TDDB data, the proposed complementary model predicts lifetime faster and more accurately, even in the wider electric field region, compared to the conventional E-model and 1/E-model.

Large Eddy Simulation of the Vortex Breakdown in Swirling Flow Using MPI Parallel Technique

  • Sung Hong-Gye;Yang Vigor
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2000.05a
    • /
    • pp.107-112
    • /
    • 2000
  • 연소실 안으로 분출되는 스월 유동의 vortex breakdown mechanism 에 대한 연구를 하였다. 3 차원 유한 체적기법과 Runge-Kutta 시간 적분법이 적용되었으며, 난류모델은 dynamic large eddy simulation (DLES)이 적용되었다. 계산 시간의 효율성과 기억용량을 효과적으로 사용하기 위하여 message passing interface (MPI) 병렬계산 기법이 적용되었다. 스월 난류 유동에 있어서 vortex breakdown 거동을 가시적으로 표착 하였는데. 이는 스월 유동에 의한 난류 응력 증대, 난류 생성/소산율 증대 및 혼합율 증대에 대한 실험적 근거를 뒷받침하는 매우 중요한 결과이다. 또한 평균 속도와 레이놀스 응력에 대한 계산 결과도 실험 결과와 비교하였다.

  • PDF

Dielectric Characteristics of $SF_{6}$ Gas Stressed by VFTO in Inhomogeneous Field (불평등전계중에서 과도과전압에 대한 $SF_{6}$가스의 절연특성)

  • 이복희;이창준;길경석;안창환
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 1995.11a
    • /
    • pp.306-309
    • /
    • 1995
  • This paper describes the dielectric characteristics of $SF_{6}$ gas in a non-uniform electric field under overvoltages. The breakdown voltage-time characteristics and the breakdown voltage-gas pressure characteristics are measured within a gas pressure range extending from 0.1 to 0.5 [Mpa] for the plane electrode system with a needle-shaped protrusion. The curvature radius of the needle protrusion is 0.5[mm]. Also, the growth process of the predischarge are simultaneously observed. As a result, it is found that the breakdown mechanism and predischarge phenomena are closely associated with the polarity and waveforms of the testing voltage.

  • PDF

A Study on the Insulation Breakdown of Mica-Epoxy Composites (Mica-Epoxy 복합재료의 절연파괴에 관한 연구)

  • Kim, Hui-Gon;Kim, Hui-Su
    • Korean Journal of Materials Research
    • /
    • v.7 no.8
    • /
    • pp.650-653
    • /
    • 1997
  • In large generators in power plants, stator winding insulations is exposed to a combination of thermal, electrical, mechanical, environmental stresses in service. These combined stresses cause insulation aging which leads to final insulation breakdown. In order to identify the breakdown mechanism, the stator winding insulation materials which are composed of mica-epoxy is analyzed by the component of materials with EDS, SEM techniques. We concluded that the potassium ions of mica are replaced by hydrogen ions at boundary area of mica-epoxy and/or mica-mica. It is proposed that through these phenomena, the conductive layers of potassium ions enable high voltage fields of multiple stresses to create voids and microcracks.

  • PDF

Analysis on the breakdown characteristics of ESD-protection NMOS transistors based on device simulations (소자 시뮬레이션을 이용한 ESD 보호용 NMOS 트랜지스터의 항복특성 분석)

  • 최진영;임주섭
    • Journal of the Korean Institute of Telematics and Electronics D
    • /
    • v.34D no.11
    • /
    • pp.37-47
    • /
    • 1997
  • Utilizing 2-dimensional device simulations incorporating lattic eheating models, we analyzed in detail the DC breakdown characterisics of NMOS trasistors with different structures, which are commonly used as ESD protection transistors. The mechanism leading to device failure resulting from electrostatic discharge was explained by analyzing the 1st and 2nd breakdown characteristics of LDD devices. Also a criteria for more robust designs of NMOS transistor structures against ESD was suggested by examining the characteristics changes with changes in structural parameters such as the LDD doping concentration, the drain junction depth, the distance between source/drain contacts, and the source junction area.

  • PDF

Statistical Analysis of Breakdown Field Distribution of PECVD SiN Films (PECVD SiN 막의 절연파괴 전계분포의 통계적 고찰)

  • Sung, Yung-Kwon;Han, Joo-Min;Oh, Jae-Ha
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 1988.05a
    • /
    • pp.84-87
    • /
    • 1988
  • cIn this paper. we evaluate the breakdown and TDDB characteristics of ammonia free ECVD SiN films which studied widely as a gate insulator to substitute the silicon dioxide because of it's superior film characteristics with the merit of low temperature process. And also, we propose a new statistical model by introduce a dispersion factor in the traditional Weibull statistics. From the comparison of experimental result, and simulation one, try to dock the breakdown mechanism and statistical analysis.

  • PDF

A.C Breakdown Characteristics in ${SF}_{6}$ in the Presence of A Small Discharge (미소 방전존재시의 ${SF}_{6}$에 대한 교류절연 파괴 특성)

  • 이광식;이동인;김인식
    • The Transactions of the Korean Institute of Electrical Engineers
    • /
    • v.39 no.3
    • /
    • pp.321-328
    • /
    • 1990
  • The effect of a small discharge on the A.C (60Hz) breakdown characteristics in SF6 gas has been studied. Various experiments were investigated while varying distance of the rod-plane electrode, the gas pressure, and the magnitude of the small discharge current. Also, the position of the discharge path was observed for the purpose of evident investigation. As the results of this study, authors clarified the shifting mechanism of the position of discharge path with the ratio Rn (E/N distribution at a certain higher tempera-ture due to the small discharge current to E/N distribution at room temperature, E:electric field strength, N:particle number density). Also, the reason for the reduction of the A.C. breakdown voltage was investigated in the presence of a small discharge current.

  • PDF

Dielectric Characteristics of $SF_6$ gas Stressed by the Oscillating Impulse Voltage in the Non-uniform Electric Fields (불평등전계중에서 진동성 임펄스전압에 대한 $SF_6$가스의 절연특성)

  • Lee, Bok-Hee;Kil, Gyung-Suk;Hwang, Kyo-Jung
    • Proceedings of the KIEE Conference
    • /
    • 1994.11a
    • /
    • pp.284-286
    • /
    • 1994
  • This paper describes the dielectric characteristics of $SF_6$ gas in non-uniform electric filed under lightning under lightning impulse and oscillating impulse voltages. The breakdown voltage-time characteristics and the breakdown voltage-pressure characteristics are measured over a pressure range extending from 0.1 to 0.5 [MPa] fur the coaxial electrode with a needle protrusion. The curvature radius of needle protrusion is 0.3[mm]. Also, the growth of the predischarge is simultaneously observed. As a result the polarity effect is pronounced, and the breakdowns voltage under the oscillating impulse voltage are higher than those under the lightning impulse voltage. It is found that the breakdown mechanism md predischarge phenomena ate closely related with the polarity and waveforms of the testing voltage.

  • PDF