Cross-sectional electron microscopy investigation of silicon amorphisation during high temperature zinc-ion bombardment

Abstract

Cross-sectional transmission electron microscopy has been applied to the characteri- sation of silicon amorphisation due to Zn+ (120 keV) ion bombardment at 110 °C. In spite of the implantation temperature used, we did not notice any annealing effect. This point is discussed in light of the low ion current used in these experiments and experimental results arising from litterature. Calculations of the energy received by the target through nuclear collisions (i.e. dam- age energy) have been recombined with concepts arising from the critical damage energy density model for the crystal to amorphous transition of silicon. Comparison of the experimental measure- ments of the extension of the amorphous layer for increasing doses with the theoretical calculations shows that a damage energy of about 10 eV.at-1 is required for silicon amorphisation. It is suggested that temperature effects are responsible for the need of higher damage energy to produce a first continuous amorphous layer than to extend this layer to greater depth. The experme- ntal observations clearly show that the roughness of the amorphous-crystalline interface is reduced