Depth distribution of Cs implanted into Si at steady-state during dual beam ToF-SIMS profiling

The steady-state depth distributions of Cs atoms implanted into a H-terminated Si surface at different energies (250 eV to 2 keV, 45° incidence angle) were studied. In situ ToF-SIMS depth profiles of the Si surface preloaded with Cs were obtained immediately after the Cs implantation using low energy Xe+ (350 eV, 45°) and O2+ (500 eV, 45°) sputter beams and a Ga+ analysis beam (15 keV, 45°). The crater depth was measured ex situ by a profilometer to calibrate the depth scale. All the Cs profiles exhibited a surface peak attributed to segregation and a maximum under the surface for both Xe+ and O2+ sputtering beams. The relative height of the surface segregation peak, the position of the maximum and the width of the Cs profiles depend on the energy of the Cs primaries. Depth profiles of adsorbed/sputter deposited Cs obtained next to the implantation craters exhibited no surface peak. A dynamic TRIM code was used to obtain the depth distribution of the implanted Cs at steady-state. The results of the simulations were compared to those obtained experimentally.