In the late 1980s, Ken Marcus developed a radically different GD source optimised for RF but it can also be used with a DC power supply. In the Marcus source the cathode block is ceramic and the RF voltage is applied to the back of the sample. The anode tube is very short and allows the plasma to expand rapidly. The Marcus source is striking by its simplicity. Using this simple design it is possible achieve similar figures of merits as with the more complex Grimm source or its derivative the Renault source. It is suited for both Optical Emission spectroscopy and mass spectroscopy. It can also be run in both the DC and the rf excitation mode. It is able to produce flat craters, same as the Grimm source. The only drawback, the author has found is a certain lack of reproducibility. The teflon o-ring used to restrict the discharge is cluttered with sputtered material during the analysis process. It needs to be replace quite regularly, if not after each analysis.
- W Grimm, Naturwiss. 54, 586 (1967).
- M Chevrier and R Passetemps, European Patent No. 0 296 920 A1 (1988).
- R K Marcus, United States Patent No. 5,006,706 (1991).
First published on the web: 15 May 2000.
Author: Richard Payling, Thomas Nelis