Emission yield for quantitative depth profile analysis by glow discharge optical emission - the influence of discharge parameters - Invited lecture

The emission yield in glow discharge optical emission spectroscopy, defined here as the integrated emission signal at some defined wavelength (spectral line) per unit sputtered mass of the element i, was investigated for the Si 288.2 nm spectral line. The purpose of the investigation was to evaluate the influence of the discharge parameters current, voltage and pressure, Three samples were used, a steel, a brass and an aluminium. The major part of the investigation was carried out with a direct current glow discharge, but comparative measurements on the same samples were also carried out with a radiofrequency glow discharge. The measured emission yields were fitted to various functions of the discharge parameters by non-linear regression software, The results show that the parameters current and voltage have a considerably larger influence on the emission yield than the pressure. The emission yield was found to increase with the current and decrease with voltage and pressure. For the investigated Si 288.2 nm line, it is concluded that the influence of pressure is nearly negligible within a normal operating range of discharge parameters.