Bremen 2017 – scientific programme

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P: Fachverband Plasmaphysik

P 25: Theory and Modeling III

P 25.3: Talk

Thursday, March 16, 2017, 09:15–09:30, HS 2010

Electric double layers at plasma-wall interfaces — •Franz Xaver Bronold and Holger Fehske — Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Deutschland

The basic response of a plasma to a macroscopic body is the formation of the plasma sheath. It is the positive part of an electric double layer whose negative part is inside the solid. A stationary sheath develops if the generation of electrons and ions in the plasma is balanced by electron and ion losses at or inside the wall. A complete modeling of the plasma sheath has to take the losses into account. It should thus cover not only the plasma physics of the positive part of the double layer but also the solid state physics affecting the negative part. For a dielectric wall we developed such a model. It is based on two sets of Boltzmann equations operating in disjunct half-spaces: One set is for the electrons and ions in the plasma half-space while the other is for conduction band electrons and valence band holes in the wall half-space. The two sets are connected by a quantum-mechanically derived matching condition for the electron distribution functions and a semi-empirical model for hole injection due to neutralization of ions at the plasma-wall interface. Essential for the model is also the merging of the space charge region with, respectively, the neutral bulk plasma and the intrinsic or extrinsic bulk of the wall. To demonstrate the feasibility of our approach we present results for a collisionless double layer developing, respectively, at an intrinsic silicon dioxide and p-type silicon surface both facing a low-temperature hydrogen plasma. --- Supported by DFG through CRC/Transregio TRR24.