Cold Cathode Sputtering in Glow Discharges

A constant challenge for industrialists in cold cathode technologies is the selection of a cathode material which exhibits suitable properties in order to improve performance. One particularly important aspect of performance is the sputter erosion of the cathode, which can lead to lamp failures. Traditionally, refractory metals have been favored for their high densities and energies of sublimation, which result in low sputter yields according to the theory due to Sigmund, and in experiment. However, this paper presents a simple theory which shows that the primary sputter yield is only one step in the liberation of sputtered material from the electrode. The energy of sublimation in fact plays an important role in the energy distribution of the sputtered material. Also, collisions in the bulk gas and the voltage characteristics of the cathode dark space should be taken into consideration for calculating the flux of liberated material. The paper presents a heuristic model of cold cathode sputtering in glow discharges with a view to elucidating the underlying physics in the process. The theory results in a reappraisal of electrode material properties that differs from the traditional view.