Charge Distribution Probe for the Measurement of Surface Charges, Internal Electric Fields and Related Fundamental Properties of Dielectric Materials

传统的方法是在绝缘体表面使用金属触点来测量绝缘体的电学和电子学性能。一项新技术显示出巨大的潜力。它可以确定无接触的，以前无法测量的材料的基本性质，特别是具有非常低的载流子浓度的材料和半导体。该技术包括测量电场梯度中的介电极化。通过反卷积的各种成分的介电极化，体和表面的贡献可以分离。因此，获得了关于表面电荷、它们的符号和密度以及它们相关的内部场的独特信息。该方法对本体极化的变化也高度敏感，如可能由缺陷的解离和移动电荷的产生引起的变化。通过施加静电场梯度并测量响应作为时间的函数，可以评估具有长松弛时间的过程，其数量级为秒到小时。这种过程可能是由于电荷载流子具有非常低的漂移迁移率，然而，这可能在决定电子器件或铁电体的长期稳定性方面起重要作用。该研究的目的是开发一种电荷分布探针，使人们能够进行高空间分辨率的测量，并确定薄绝缘层的电子特性。

The electric and electronic properties of insulators are difficult to measure by conventional methods which apply metal contacts to the insulator surfaces. A new technique has shown great potential. It enables determination of contact-free, previously unmeasurable fundamental properties of materials, especially of materials with very low charge carrier concentrations and of semiconductors. The technique consists of measuring the dielectric polarization in an electric field gradient. By deconvoluting the various components of the dielectric polarization, bulk and surface contributions can be separated. Thus, unique information is obtained about surface charges, their sign and density as well as their associated internal field. The method is also highly sensitive to changes in the bulk polarization such as may be caused by the dissociation of defects and generation of mobile charges. By applying a static electric field gradient and measuring the response as a function of time, processes with long relaxation times, of the order of seconds to hours, can be evaluated. Such processes may be due to charge carriers with very low drift mobilities which, however, may play an important part in determining the long-term stability of electronic devices or ferroelectrics. The objective of the research is to develop a Charge Distribution Probe which allows one to perform measurements with high spatial resolution and determine the electronic properties of thin insulator layers.