Simple experiment on the sputtering rate of solids in gas discharges

Abstract

We present a very simple and sensitive method to measure the sputtering rate of solid materials in stationary low-pressure gas discharges. The method is based on the balance of the centrifugal force and the confinement electric force acting on a single electrically charged dust particle in a rotating environment. We demonstrate the use and sensitivity of this method in a capacitively coupled radio frequency argon discharge. We were able to detect a reduction of 10 nm in the diameter of a single dust particle. Published by AIP Publishing. [http://dx.doi.org/10.1063/1.4985080] Low-pressure gas discharges in industrial and laboratory applications are mostly confined in a vacuum chamber made of metallic and/or dielectric solid materials. These surfaces define the boundary conditions (temperature, electric potential, etc.) and provide the most significant loss (and sometimes source) channels for the charged particles by electric conduction, surface recombination, electron emission, etc. As gas discharges are driven-dissipative systems, where the charge production processes (ionization and emission) and loss channels (recombination and absorption) are separated in both space and time, the geometrical properties and the boundary conditions have significant effects on the overall plasma parameters such as the distributions of charged species densities, temperature, and electric potential. To date the effect of solid surfaces at the edges of gas discharge plasmas can only be taken into account by applying overly simplified phenomenological models. 1 The data for the different processes in these models, like secondary electron emission yield, electron reflection probability, sputtering yield, etc., are not available in general for any combination of gas and solid materials. In the rare cases where there are experimental data published, the experiments are mostly performed in a high vacuum environment using mono-energetic beams of electrons or ions and clean surfaces.2,3 These conditions are very different from discharge conditions, where the background gas is able to modify the surface.To advance the field of gas discharge physics, a deeper understanding of the mutual interaction between the discharge plasma and the surfaces is needed. Increasingly, effort is being put into research targeting the combined, self-consistent description of the solid-plasma system, the so called "plasma interface" at the microscopic level of individual atoms and electrons including quantum effects. 4 At some stage of these efforts, any new results will have to be validated against actual phenomenological models and experimental data obtained under real discharge conditions. The aim of this study is to provide a simple and fundamental experimental technique for determination of the sputtering rate of solid materials in gas discharges with high accuracy and sensitivity.5 This method can be used to provide experimental data useful for both present phenomenological models and future fundamental models describing sputtering, one of the important p...

Molecular dynamics investigation of soliton propagation in a two‐dimensional Yukawa liquid

“…In addition to fundamental manybody physics dusty plasmas provide a very sensitive tool for the detailed investigation of mutual plasma-surface interactions. Recent studies include the investigations of the effect of external fields on the local plasma properties around a dust particle [64], and the sputtering rate of the solid dust surface with nanometer resolution in [65].…”