Different methods for the determination of damage profiles in Si from RBS-channeling spectra: a comparison

Abstract

RBS-channeling spectra of deep ion implants in silicon were analyzed to extract the displaced atoms depth profiles by different methods. In all cases it was assumed that defects in as-implanted samples can be described as atoms randomly displaced from the lattice sites. In the first method, based on the two beam model, the dechanneling induced by defects was calculated either linearly or following a recently developed semi-empirical formula. In the second method the analyzing beam was divided into a greater number of components to follow the transverse energy distribution of the ions. Finally a three-dimensional Monte Carlo 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 essentially the same profiles. On the contrary they considerably disagree in other cases. Moreover, Monte Carlo calculations indicate that to obtain reliable results it is necessary to take into account a correct description of the channeling energy loss process during ion penetration into a disordered crystal.