Regimes in depositing dielectric barrIer discharges

该项目旨在更好地了解常压低温等离子体低成本薄膜沉积工艺的放电发展和结构基础知识。等离子体技术是通过沉积薄保护层或功能层来对表面进行改性的关键技术。这通常是通过低压等离子体来完成的，这需要大量的真空设备，需要批量处理，并且无法对物体进行在线处理。在大气压下工作的等离子体，如介质阻挡放电(DBDS)，可以克服这些缺点，因为它已经在含硅薄膜中得到证明。然而，DBD通常是非常不均匀的，因此层的沉积将是不均匀的。对放电形成的基本物理原理，特别是对层沉积的条件，仍然缺乏充分的了解。例如，在含有前体分子(沉积单体)的混合气体中，对放电均匀度的控制很少被研究。此外，由于电荷载流子的充电和发射对DBDS的运行至关重要，表面的层沉积会影响DBDS的放电特性。此外，随着频率的增加，对这种放电的控制仍然很差，从而导致气体中的功率消耗，可以极大地改变在气相中产生并与表面相互作用的等离子体的流动和能量。为了研究这种过程，并为数值模拟提供实验基准，将通过电学和光学诊断的手段来研究特殊的专用DBD布置。基于这些结果，与层沉积研究的关联将导致对此类过程控制的更好理解。将详细研究如何通过操作参数和放电几何来控制不同的放电模式(丝状DBD、均匀DBD、图案化和自组织DBD)。一方面，我们将研究单丝在丝状模式下的放电发展，特别关注表面过程。因此，可以预见介质(性质、厚度)的系统变化以及通过电光效应对介质表面电荷的定量测量。为了研究表面荷电的作用，还预见了液体介质的表面荷电研究，其中沉积的电荷可以从有源放电区移动。另一方面，利用一种新颖的具有结构电极的DBD装置，研究了放电通道与柱之间的集体效应以及放电形成的径向动力学。

This project aims to a better fundamental knowledge of discharge development and structure for low cost thin film deposition processes using low temperature plasmas at atmospheric pressure.Plasma technology is a key technology for the modification of surfaces by deposition of thin protective or functional layers. It is usually done by means of low-pressure plasmas, which require extensive vacuum equipment, require batch processing and disable in-line treatment of objects. Plasmas operated at atmospheric pressure, such as Dielectric Barrier Discharges (DBDs) can overcome these disadvantages as it could already be demonstrated for silicon containing films. However DBDs are usually strongly non-uniform and thus deposition of layers will be inhomogeneous. A full understanding of the underlying physics of discharge formation is still missing, in particular for conditions for layer deposition. For example the control of discharge uniformity in gas mixtures containing precursor molecules (deposit monomers) is rarely studied. Furthermore, layer deposition on surfaces can influence the discharge characteristics as the charging and emission of charge carriers is crucial for the operation of DBDs. Furthermore, the control of such discharges is still poor as an increase of the frequency, and consequently of the power dissipated in the gas, can drastically change the flow and the energy of the plasma species created in the gas phase and interacting with the surface.To study such processes and give experimental benchmarks for numerical simulation special dedicated DBD arrangement will be studied by means of electrical and optical diagnostics. Based on these results the correlation with layer deposition studies will result in a better understanding of the control of such processes. In detail it will be studied, how distinct discharge modes (filamentary DBD, homogenous DBD, patterned and self-organized DBD) can be controlled by means of operation parameters and discharge geometry. On one hand the discharge development of monofilaments in the filamentary mode will be investigated with special attention on the surface processes. Therefore systematic variation of the dielectrics (nature, thickness) as well as a quantitative measurement of the surface charges on the dielectrics by means of electro-optical effects are foreseen. In order to study the role of surface charging studies with liquid dielectrics, where deposited charges can be moved from the active discharge zone are also foreseen. On the other hand utilizing a novel DBD arrangement with structured electrode the collective effects between discharge channels and columns as well as the radial dynamics of discharge formation will be studied.