Abstract
A formula to calculate the electrical breakdown strength EBD of solid dielectrics is derived based on a model of electron impact ionization and multiplication. This formula takes into account three types of parameters that influence EBD, namely, dielectric parameters (dielectric temperature and atom density), impact ionization parameters (ionization energy and probability), and multiplication parameters (number of initial electrons and number of generations of secondary electrons). The predictions of this formula are found to agree with experimental results. In addition, comparisons are made between the results of this formula and those of 38-generation-electron theory and other models, which show that the proposed formula is most appropriate to describe the breakdown of solid dielectrics on a nanosecond time scale.
Highlights
Solid dielectric breakdown is one of the basic breakdown phenomena occurring in nature and has been studied for nearly 100 years.1 Depending on the mechanisms involved, there are several types of solid dielectric breakdowns, including electrical breakdown, thermal breakdown, electromechanical breakdown, electrochemical breakdown, and erosion breakdown
This is consistent with the physical mechanism, according to which the larger the energy bandgap, the harder it is for breakdown to occur, which results in a larger EBD
The model based on 38-generation-electron theory can be considered as a specific case of the electron impact ionization and multiplication model, whereas the improved model in this paper can be used for the calculation of EBD in many cases, one of which is the nanosecond-pulse breakdown of a solid dielectric
Summary
Solid dielectric breakdown is one of the basic breakdown phenomena occurring in nature and has been studied for nearly 100 years. Depending on the mechanisms involved, there are several types of solid dielectric breakdowns, including electrical breakdown, thermal breakdown, electromechanical breakdown, electrochemical breakdown, and erosion breakdown (electrical treeing breakdown). Electrical breakdown has an electronic origin and can be further divided into two subtypes: intrinsic breakdown and avalanche breakdown The former is initiated by electron impact and ionization, whereas the latter involves an avalanche phenomenon. Where ΔI is the ionization energy or energy bandgap, q is the electron charge (1.6 × 10−19 C), Eop is the applied field, and λ is the electron mean free path In this criterion, ΔI and λ are the two main factors influencing the value of the electric breakdown field EBD at which breakdown occurs.
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