Investigation of nonlinear oscillations in the gas discharge-semiconductor system: effect of different fluid modelling approaches

Yeşil, Cihan
The work deals with the study of nonlinear oscillations in a system, consisted of planar glow discharge layer, coupled to a high-ohmic semiconductor layer. The whole system is sandwiched between two planar electrodes, to which the DC voltage is applied. The discharge models are developed in Comsol Multiphysics (v5.2), and based on fluid description of plasma, with drift-diffusion approximation for charged particle fluxes. Numerical tests are carried out for the discharge in Nitrogen, with GaAs semiconductor layer. We first derived and tested three different fluid models for DC glow discharge: the "simple" model, where the ionization is defined by the Townsend approximation, and two "extended" models with more detailed sets of plasma-chemical reactions. Accuracy and reliability of these models are analyzed by making comparison between the computed and experimental current-voltage characterics. Then, these models are applied to numerical investigation of the gas discharge-semiconductor system. First, the homogeneous stationary states of the system are identified. Then, the analysis of these states allows to develop bifurcation curves in the parameter space, separating the region where the plasma is stable from the region where it performs the homogeneous oscillations. Comparison with the experimental data allows to determine the accuracy and the ranges of applicability of different modelling approaches.


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In this thesis, numerical modelling of temporal and spatial pattern formation in the planar layered system, consisted of a DC driven planar gas discharge layer, coupled to high ohmic semiconductor layer, is carried out in 1D and 2D Cartesian geometry. Numerical model includes continuity equations for ions and electrons, the Poisson equation for the electric field, the energy balance equation for the background gas. The conditions correspond to a transition from the Townsend regime to the glow discharge. Cal...
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We studied asystem consisted of a planar glow discharge layer with short length in the forward direction and wide lateral dimensions, which iscoupled to a semiconductor layer with low conductivity. The whole structure is sandwiched between two planar electrodes, to which a dc voltage is applied. Experiments show that such a system can create different homogeneous stationary and homogeneous oscillating modes, patterns with spatial and spatiotemporal structures. We develop...
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A short gas-discharge layer sandwiched with a semiconductor layer between planar electrodes shows a variety of spatiotemporal patterns. We focus on the spontaneous temporal oscillations that occur while a dc voltage is applied and while the system stays spatially homogeneous; the results for these oscillations apply equally to a planar discharge in series with any resistor with capacitance. We define the minimal model, identify its independent dimensionless parameters, and then present the results of the fu...
Citation Formats
C. Yeşil, “Investigation of nonlinear oscillations in the gas discharge-semiconductor system: effect of different fluid modelling approaches,” M.S. - Master of Science, Middle East Technical University, 2018.