4.5.2.1 Simplified Molecular Method

By the simplified molecular method just one (significant) atom species of the molecule is consider rigorously, which means that just the implanted distribution of this species is calculated. As well in case of BF$_2$ as of B$_{10}$H$_{14}$ ion implantation boron is the significant species. All other atom species in the molecule are considered as being not relevant for the simulation. Just their influence on the trajectories of the significant species by producing additional damage in a crystalline target is taken into account.

When simulating the implantation of a molecular ion with the simplified molecular method a simulation of a single atomic ion is performed whose implantation energy is equivalent to the reduced energy calculated by (4.6).

The simplified method is only applied in combination with the modified Kinchin-Pease damage model. The higher damage generation rate of the molecular ion is modeled by modifying the recombination parameters of the implanted species (Sec. 3.3.5). The higher dose rate according to the larger number of similar atoms in the molecule is treated by multiplying all concentrations with the number of atoms of this species in the molecule. For instance in case of B$_{10}$H$_{14}$ a factor of 10 is used. Tab. 4.2 summarizes the modified recombination parameters for the supported molecular ions.

Table 4.2: Parameters for the empirical recombination model for different molecular ion species.

Ion species	$f_{rec}$	$N_{sat}$
BF$_2$	1.0	$5{\cdot}10^{22}$cm$^{-2}$
B$_{10}$H$_{14}$	0.2	$5{\cdot}10^{22}$cm$^{-2}$

A fundamental requirement to apply the simplified molecular method is that the distributions of all implanted atom species have a similar shape, because it is assumed that the damage distribution generated by the neglected atom species can be approximated by multiplying the damage profile generated by the significant atom species.