Burning voltages of vacuum arcs were measured for 54 cathode materials and compared with literature data. As anticipated, a correlation between the arc burning voltage and the plasma temperature was found. However, more importantly, a correlation between the cohesive energy of the cathode material and the arc burning voltage could be demonstrated. This link between a cathode material property, the cohesive energy, and a discharge property, the arc burning voltage, is essential for the operation of the vacuum arc discharge because is determines the plasma temperature. Energy balance considerations show that this “cohesive energy rule” is responsible for several other secondary relationships, such as the correlation between the mean ion charge state and the boiling temperature of the cathode.

Optical emission spectroscopy in the range from 200 to 800 nm was applied for investigation of the copper plasma produced by a metal vapor vacuum arc plasma source. The experiments were conducted for the cases when the plasma was guided by straight and Ω-shaped curved solenoids as well as without solenoids and, also, for different vacuum conditions. It was found that, besides singly and doubly charged ions, a relatively high concentration of excited neutral copper atoms was present in the plasma. The relative fraction of excited atoms was much higher in the region close to the cathode surface than in the plasma column inside the solenoid. The concentration of excited neutral, singly-and doubly-ionized atoms increased proportionally when the arc current was increased to 400 A. Some weak lines were attributed to more highly ionized copper species and impurities in the cathode material.

Molybdenum-containing amorphous carbon (a-C:Mo) thin films were prepared using a dual-cathode filtered cathodic arc plasma source with a molybdenum and a carbon (graphite) cathode. The Mo content in the films was controlled by varying the deposition pulse ratio of Mo and C. Film sheet resistance was measured in situ at process temperature, which was close to room temperature, as well as ex situ as a function of temperature (300-515 K) in ambient air. Film resistivity and electrical activation energy were derived for different Mo and C ratios and substrate bias. Film thickness was in the range 8-28 nm. Film resistivity varied from 3.55×10 -4 Ω m to 2.27×10 -6 Ω m when the Mo/C pulse ratio was increased from 0.05 to 0.4, with no substrate bias applied. With carbon-selective bias, the film resistivity was in the range of 4.59×10 -2 and 4.05 Ω m at a Mo/C pulse ratio of 0.05.The electrical activation energy decreased from 3.80×10 -2 to 3.36×10 -4 eV when the Mo/C pulse ratio was increased in the absence of bias, and from 0.19 to 0.14 eV for carbonselective bias conditions. The resistivity of the film shifts systematically with the amounts of Mo and upon application of substrate bias voltage. The intensity ratio of the Raman D-peak and G-peak (I D /I G ) correlated with the pre-exponential factor (σ 0 ) which included charge carrier density and density of states.

We have developed a new technique for stable production of lanthanide negative ions in a cesium sputter ion source without damage to the ionizer. Lanthanide elements sticking to a cesium ionizer deteriorate an ionization efficiency of the ionizer because of their characteristics such as low vapor pressures and low work functions. We have resolved the problem to make a sputter cathode that has a predrilled double layer structure. Cerium oxide powder pressed in the cathode pellet was covered by tungsten and drilled. Using this cathode, we achieved smaller solid angle emission of the sputtered lanthanide elements from the bottom of the drilled hole, and most of them could pass through the center hole of the ionizer. As a result, damage to the ionizer decreased, and stable operation of the ion source was successfully achieved with a cerium oxide beam current of 600 nA for 24 h continuous operation. The technique was applied for production of other rare earth ions.

The authors describe a method for the measurement of secondary electron emission coefficients and demonstrate the use of this approach for the measurement of secondary electron yields for titanium, copper, and carbon ions incident upon an aluminum target. The method is time-resolved in that a series of measurements can be obtained within a single ion beam pulse of several hundred microseconds duration. The metal ion beams were produced with a vacuum arc ion source, and the ratio of secondary electron current to incident ion current was determined using a Faraday cup with fast control of the electron suppressor voltage. The method is relatively simple and readily applied and is suitable for measurements over a wide parameter range. The secondary yields obtained in the present work are of relevance to the measurement of ion current and implantation dose in plasma immersion ion implantation.Index Terms-Ion beam bombardment, ion beams, secondary electron yield, secondary emission, vacuum arc ion source, vacuum arc plasma.