Kinetics of electric double layers at dielectric plasma-facing solids

面向电介质等离子体的固体的双电层动力学

• 批准号: 407495057
• 负责人: Privatdozent Dr. Franz Xaver Bronold
• 金额: --
• 依托单位: Institut für Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/407495057?language=en
• 关键词: Kinetics; electric; double; layers; dielectric

A solid surface in contact with an ionized gas collects electrons more efficiently than it looses electrons due to the recombination of ions or the deexcitation of radicals. It thus acquires a negative charge which in turn triggers an electron-depleted region in front of it. The most fundamental manifestation of the interaction of a solid with a plasma is thus the build-up of an electric double layer at the interface. It has been however hardly studied. Only the positve part of the double layer - the plasma sheath - has been investigated in great detail, the negative part in contrast, residing either inside or on top of the surface, depending on the electronic structure, received little attention. Little is also known about the plasma loss at the surface, which for dielectric surfaces has to occur via recombination of electron-hole pairs. To tap the full potential of hybrid electronics - an emerging line of plasma research combining elements of gaseous and semiconductor electronics - it is however crucial to understand the loss process quantitatively, that is, to determine explicitly the fate of the plasma-induced surplus charges inside the solid. Linking plasma production in the gas to plasma loss inside the solid microscopically and describing thereby the kinetics of the electric double layer at the plasma-solid interface is the goal of this project. We develop a kinetic theory specifically for a floating dielectric plasma-solid interface, taking its partial reflectivity, its electronic structure, and collisions on both sides of it into account. Our approach is based on two sets of Boltzmann equations, one for the electrons and ions inside the plasma and one for the electrons and holes inside the dielectric, the Poisson equation for the electric potential energy, and matching/boundary conditions at the interface/far away from it. Utilizing the different time-scales of intraband scattering and interband recombination, we derive a set of equations describing for the first time the charge transfer across the interface selfconsistently with the charge dynamics on both sides of it. Solving the set of equations iteratively, with the Grinberg-Luryi approach for determining distribution functions in halfspaces as the central element, we will be able to identify solid-based ways to control the plasma-induced space charge inside the solid as well as the recombination process itself (radiative vs. non-radiative) and may thus open up new possibilities for hybrid electronics.

与电离气体接触的固体表面收集电子的效率比由于离子复合或自由基失激发而失去电子的效率更高。因此，它获得了负电荷，而负电荷反过来又触发了它前面的电子枯竭区域。因此，固体与等离子体相互作用的最基本表现形式是在界面处形成双电层。然而，几乎没有人对它进行研究。只有双层的正极部分--等离子体鞘--得到了非常详细的研究，相比之下，负极部分，根据电子结构的不同，要么位于表面内部，要么位于表面的顶部，很少被关注。对表面的等离子体损失也知之甚少，对于介电表面，这必须通过电子-空穴对的复合而发生。然而，要挖掘混合电子学的全部潜力--一种结合了气体和半导体电子学元素的新兴等离子体研究领域--关键是要定量地了解损失过程，也就是明确确定等离子体在固体中诱导的多余电荷的命运。在微观上将气体中的等离子体产生与固体中的等离子体损失联系起来，从而描述等离子体-固体界面上的双电层的动力学是本项目的目标。我们发展了一个浮动介质等离子体-固体界面的动力学理论，考虑了它的部分反射率，它的电子结构，以及它两侧的碰撞。我们的方法基于两组Boltzmann方程，一组用于等离子体内的电子和离子，另一组用于介质内的电子和空穴，泊松方程用于电势能，以及界面/远离界面的匹配/边界条件。利用带内散射和带间复合的不同时间尺度，我们首次导出了一组描述界面电荷转移的方程，该方程与界面两侧的电荷动力学是一致的。迭代地求解这组方程，以Grinberg-Luryi方法确定半空间中的分布函数为中心元素，我们将能够识别基于固体的方法来控制固体内部的等离子体诱导空间电荷以及复合过程本身(辐射和非辐射)，从而可能为混合电子学打开新的可能性。