Interference phenomena at trasparent layers in glow discharge optical emission spectrometry

At the performance of depth profiling by glow discharge optical emission spectroscopy (GD-OES) the intensities of optical emission lines of sample and sputter gas elements are measured in depen-dence on the time of sputtering. Radio-frequency (rf) sputtering extended the field of application to nonconducting samples includ-ing transparent layers. For transparent coatings in the thickness range up to some micrometers, oscillations of measured intensities were observed. This behavior is explained by a thin-film interfer-ence effect and discussed for three different materials, i.e., S'021 T'02, and BaTi03. As a result, a new procedure for the determi-nation of either layer thickness or refractive index from G13-OES depth profiles is presented. This effect has to be considered for quantitative GD-OES analysis as well.