SPUTTERING YIELDS FOR 0.1 - 6 keV PROTONS INCIDENT ONTO MOLYBDENUM AND GRAPHITE TARGETS

Abstract

In molybdenum, the sputtering yield at ambient temperature was obtained by in situ measurement of Auger electron signals from sputtered molybdenum atoms deposited onto substrate. An electro-micro-balance was used to calibrate the Auger signals. The present experimental sputtering yield for molybdenum in the proton energy above 1 keV is about three times as large as the experimental one obtained by Finfgeld. Below 1 keV it rapidly decreases with decreasing energy, and reaches the small value of 1.9×10−4 atoms/ion at 0.15 keV. In pyrolytic graphite, physical sputtering yield at 500 °C was measured by the same way as for molybdenum. The absolute value of the yield in pyrolytic graphite is about an order of magnitude as large as that in molybdenum, whereas the energy dependence is very similar to the molybdenum case. In addition, chemical sputtering (methane production) yield for pyrolytic graphite was measured at 1 keV, whose temperature dependence shows the maximum value of about 0.1 CH4 molecules/ion near 800 K.