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Analysis of the mechanisms of dielectric breakdown in ceramic materials

陶瓷材料介电击穿机理分析

基本信息

批准号：
198021916
负责人：
Professor Dr. Gerold A. Schneider
金额：
--
依托单位：
Institut für Keramische Hochleistungswerkstoffe
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2011
资助国家：
德国
起止时间：
2010-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/198021916?language=en
关键词：
Analysis mechanisms dielectric breakdown ceramic

项目摘要

Our experiments from the first project period showed that space charge limited conduction (SCLC) is the dominating conduction mechanism in 5µm-5mm thick ceramics at dielectric breakdown. This conduction mechanism is also the reason for the thickness-dependence of the breakdown strength. This means that all breakdown models which assume ohmic conduction at breakdown for 5µm-5mm thick ceramics are incorrect. In the first project period, we developed a breakdown model in analogy to the energy release rate concept known from fracture mechanics. This breakdown model is able to explain the experimentally found thickness-dependence of the breakdown strength as well as the dependence of the breakdown strength to the permittivity.In the following the scientific objectives of the renewal proposal are described:1. The developed breakdown model will be validated. The model predicts a dependence of the breakdown strength to the length of conducting filaments which initiate the breakdown process. These conducting filaments will be imitated experimentally by electrically conducting channels of different lengths which will be introduced by FIB (Focused Ion Beam) into defect-free substrates. The breakdown strength of these so prepared substrates will be correlated to the length of the FIBed channels and compared to the prediction of the breakdown model.2. The conduction mechanism of SCLC is thickness-dependent which means that the onset of SCLC in shifted to higher voltages in thicker samples. Therefore, there should be a limiting thickness above which the conduction mechanism will not be SCLC at breakdown anymore. In order to validate this assumption, experiments on thick samples are planned. The thickness is chosen that way that SCLC cannot establish before breakdown happens. In this third thickness range the breakdown strength should at least show a different thickness-dependence compared to what was already measured. The newly proposed breakdown model is not valid for this thickness range anymore and we can define an upper validity limit for the model in terms of sample thickness. 3. The breakdown strength of stacks should be evaluated. The dominating conduction mechanism at breakdown is SCLC. Therefore, it can be assumed that the breakdown of a layered sample cannot be explained by the linear ohmic model of a layered dielectric. Here, the influence of stacks with a thickness ranging in the thickness-dependent as well as in the thickness-independent breakdown strength range will be evaluated. Besides stacks of same material also stacks of different materials in terms of permittivity will be tested. We expect that the breakdown strength of a high-permittivity material can be enhanced by a thin layer of a low-permittivity material. This is of notable interest for technical application. In order to describe the breakdown strength of layered samples the linear model of a layered dielectric should be enhanced by SCLC.

我们在第一个项目期间的实验表明，空间电荷限制导电（SCLC）是5µm-5 mm厚陶瓷在介质击穿时的主要导电机制。这种传导机制也是击穿强度的厚度依赖性的原因。这意味着所有假设5µm-5 mm厚陶瓷击穿时欧姆导电的击穿模型都是不正确的。在第一个项目期间，我们开发了一个类似于断裂力学中已知的能量释放率概念的击穿模型。该击穿模型能够解释实验发现的击穿强度的厚度依赖性以及击穿强度对介电常数的依赖性。将对开发的故障模型进行验证。该模型预测的击穿强度的依赖性的长度的导电丝启动击穿过程。这些导电细丝将通过不同长度的导电通道进行实验模拟，这些导电通道将通过FIB（聚焦离子束）引入到无缺陷的衬底中。这些如此制备的衬底的击穿强度将与FIB通道的长度相关，并与击穿模型的预测进行比较。SCLC的导电机制是厚度依赖性的，这意味着SCLC的开始在较厚的样品中移向较高的电压。因此，应该存在一个极限厚度，在该厚度之上，传导机制在击穿时将不再是SCLC。为了验证这一假设，厚样品的实验计划。厚度的选择使得SCLC在击穿发生之前不能建立。在该第三厚度范围中，击穿强度应当至少显示出与已经测量的相比不同的厚度依赖性。新提出的击穿模型不再适用于此厚度范围，我们可以根据样品厚度定义模型的有效性上限。3.应评估电池堆的击穿强度。击穿时的主要导电机制是SCLC。因此，可以假定，分层样品的击穿不能用分层电介质的线性欧姆模型来解释。在这里，将评估厚度依赖性击穿强度范围内以及厚度无关击穿强度范围内的厚度的叠层的影响。除了相同材料的叠层之外，还将测试不同材料的叠层的介电常数。我们期望高介电常数材料的击穿强度可以通过低介电常数材料的薄层来增强。这对于技术应用来说是值得注意的。为了描述层状样品的击穿强度，层状介质的线性模型需要用SCLC来增强。