MEASUREMENT OF ELECTRON-EMISSION DUE TO ENERGETIC ION-BOMBARDMENT IN PLASMA SOURCE ION-IMPLANTATION

An experimental procedure has been developed to measure electron emission due to energetic ion bombardment during plasma source ion implantation. Spherical targets (radius = 2 cm) of copper, stainless steel, graphite, titanium alloy (Ti-6Al-4V) and aluminum alloy (6061) were biased negatively to 20, 30, and 40 kV in argon and nitrogen plasmas. A Langmuir probe was used to detect the propagating sheath edge and a Rogowski transformer was used to measure the current to the target. The measurements of electron emission coefficients compare well with those measured under similar conditions [B. Szapiro and J. J. Rocca, J. Appl. Phys. 65, 3713 (1989)].