Sputtering yields of niobium by deuterium in the keV range

The sputtering yields of ∼600 Å niobium films bombarded by 3–8 keV D+ ions have been measured. Rutherford back-scattering of 150 keV H+ ions has been used as a probe to measure the decrease of film thickness due to sputtering. A sputtering yield of S=4 × 10−3 atoms/ion was found which is only weakly dependent on the energy. The result is about a factor of two lower than expected from extrapolating measurements made by Summers et al. 2 at higher energies. The discrepancy may be due to differences in film structure, contamination by oxygen, and/or differences in the measuring methods, but cannot at the moment be clearly accounted for.