Comparison of ion-excited Auger electron emission and secondary ion emission from silicon bombarded with noble gas ions

Abstract

The projectile-energy dependence of Si-LMM Auger electron emission and Si 2+ and Si 3+ secondary ion emission from silicon has been measured in situ for bombardment with 2–30 keV Ne, Ar, Kr, and Xe ions at an angle of incidence of 45°. Si 2+ and Si 3+ emission has also been studied at normal incidence. It was found that all signals increase very rapidly with increasing projectile energy, I ∝ E n , with n up to 5. The low energy threshold, E th, depends upon the maximum energy transfer between primary ion and target atom. The intensities of Auger electrons and multiply charged secondary ions are directly proportional to each other. Si 2+ and Si 3+ are thus produced as a result of Auger deexcitation of sputtered Si ions containing a 2p hole. Excitation is mostly due to symmetric SiSi collisions in the bulk. Additional excitation due to direct projectile-target interaction is observed in the case of Ar impact. The intensity ratios I(45°)/( I(0°) for Ne, Kr, and Xe bombardment increase by a factor of three between 3 and 10 keV.