DIFFERENT METHODS FOR THE DETERMINATION OF DAMAGE PROFILES IN SI FROMRBS-CHANNELING SPECTRA - A COMPARISON

RBS-channeling spectra of deep ion implants in silicon were analyzed t o extract the displaced atoms depth profiles by different methods, in all cases it was assumed that defects in as-implanted samples can be d escribed as atoms randomly displaced from the lattice sites. In the fi rst method, based on the two beam model, the dechanneling induced by d efects was calculated either linearly or following a recently develope d semi-empirical formula, In the second method the analyzing beam was divided into a greater number of components to follow the transverse e nergy distribution of the ions, Finally a three-dimensional Monte Carl o code containing a detailed description of each ion path was used to identify the limits of the previous approaches, it is shown that when high amounts of damage are considered all the methods produce essentia lly the same profiles. On the contrary they considerably disagree in o ther cases, Moreover, Monte Carlo calculations indicate that to obtain reliable results it is necessary to take into account a correct descr iption of the channeling energy loss process during ion penetration in to a disordered crystal.