Introduction Surface and Interface Analysis by Glow Discharge Spectrometry
The possibilty of performing surface and interface analysis using a glow discharge source is linked to the flat sputter craters which can be created with this technique. For good depth resolution in depth profiling, it is important to choose the source parameters correctly to obtain sputter craters with flat bottoms
Flat bottomed craters correspond to the ‘abnormal’ discharge region, the region for which all of the cathode surface participates in the discharge. Concave craters generally arise when the potential is too low for the sample at the chosen pressure; convex craters are the reverse, the potential is too high for a given sample and pressure.
When operating with constant power, the pressure is adjusted before analysis to give a flat bottomed crater.
In bulk analysis, the crater shape is generally not important. High power and pressure (high voltage and current) are usually selected to increase sputtering to gain the maximum signal. These hard conditions may have to be reduced for temperature sensitive materials. For many non-conductive materials, being particularly sensitive to heat, an efficient sample cooling is required. In some cases, such as organic paint coating, cooling with liquid nitrogen helps stabilising the discharge. Also pulsed glow discharge as been found to reduce the thermal stress on the sample surface.
- M Bouchacourt and F Schwoehrer, in R Payling, D G Jones and A Bengtson (Eds), Glow Discharge Optical Emission Spectrometry, John Wiley, Chichester (1997), pp 62-67;
- M S Marychurch and R Payling, in R Payling, D G Jones and A Bengtson (Eds), Glow Discharge Optical Emission Spectrometry, John Wiley, Chichester (1997), pp 67-69.
- Th. Nelis, J. Pallosi; Glow Discharge as a tool for surface and Interface analysis; Applied Spectroscopy Review, 41; 2006; pp 227-258; DOI 10.1080/05704920600620345
Author: Richard Payling & Thomas Nelis; First published on the web: 1 June 2000.