Ion energy distribution measurements of low-energy ion beams extracted from a hot cathode DC ion source

Ion energy distribution function (IEDF) of low-energy ion beams extracted from a hot cathode DC ion source have been measured and analyzed using a retarding potential analyzer. Measurements revealed that the height of the IEDF peaks increased in proportion to the discharge current of the ion source. In terms of downstream gas pressure, an optimum value of the height of the IEDF peak was observed at 0.13 Pa at different discharge currents. Full width at half maximum measurements showed an increase in energy spread (ΔE) with increasing discharge current. With a discharge current of 30 mA and 0.13 Pa pressure, ΔE was almost constant against the change in extraction potentials from 20 to 60 V. Typical ΔE was at most 10% of the extraction beam energy. The ion beam current density was in the mA/cm2 range