Study of low energy Si-5(-) and Cs- implantation induced amorphization effects in Si(100)

摘要

The damage growth and surface modifications in Si(1 0 0), induced by 25 keV Si-5(-) cluster ions, as a function of fluence, phi, has been studied using atomic force microscopy (AFM) and channelling Rutherford backscattering spectrometry (RBS/C). RBS/C results indicate a nonlinear growth in damage from which it has been possible to get a threshold fluence, phi(0), for amorphization as 2.5 x 10(13) ions cm(-2). For phi below phi(0), a growth in damage as well as surface roughness has been observed. At a phi of 1 x 10(14) ions cm(-2), damage saturation coupled with a much reduced surface roughness has been found. In this case a power spectrum analysis of AFM data showed a significant drop in spectral density, as compared with the same obtained for a fluence, phi < phi(0). This drop, together with damage saturation, can be correlated with a transition to a stress relaxed amorphous phase. Irradiation with similar mass Cs- ions, at the same energy and fluence, has been found to result in a reduced accumulation of defects in the near surface region leading to reduced surface features.