Interplay between the Coulomb explosion and vicinage effects studied using H/sub 2//sup +/ molecules under channeling conditions

Abstract

The aim of this work is to investigate how the mean energy loss and straggling due to H2 + molecules interacting with silicon are affected by the Coulomb explosion and vicinage effects. To that end, a SIMOX-type sample made up of 18 O and with an appropriate 18O marker grown over the surface of crystalline Si was employed, allowing to carry out the measurements through the 18 O (p, α)15N resonant reaction at 151.2 keV under channeling and random directions. The results show that the mean energy loss associated with the Coulomb explosion and vicinage effects are similar and amount each to about 2% of the total mean energy loss. The comparison of the energy straggling obtained for molecular beams at random and the well-aligned 100 direction shows a larger value for the aligned case, which is interpreted as a result of the Coulomb explosion along the channel direction. The experimental results are also discussed in terms of Monte Carlo simulations.