Scattering of keV hydrogen and helium ions and neutrals from oxygen covered surfaces

Using a time-of-flight technique, we have measured the energy distributions of hydrogen and helium backscattered from well characterized silicon targets. Silicon single crystal samples were first oxidized to selected depths and then analyzed using Auger depth profiling and MeV He channeling. The energy spectra have been measured and are compared to a computer simulation theory. For the cases considered the oxide layer reduced the reflection coefficient by a maximum of approximately 25% for He and less than half of this amount for H.