Stopping Cross Sections for 0.3- to 1.7-MeV Helium Ions in Silicon and Silicon Dioxide

Stopping cross sections of helium ions with energy 0.3–1.7 MeV have been measured with a systematic error of ±1.6% in silicon and ±1.3% in amorphous silicon dioxide. The probable random error of the measurements is estimated to be 2.3%. Experimentally, a backscattering technique is used in which the ions are scattered through 150° from a heavy mass atom on the back surface of the target film. The stopping cross-section data were obtained using a 1114-Å-thick silicon target film and a 1030-Å silicon dioxide film. The results for SiO2 indicate a deviation from the Bragg-Kleeman rule of additivity of atomic stopping cross sections.