Subject: How do Ion's implanted into silicon change the area into dopant sites?

In the Semiconductor field, Ion implanters use ions as the dopant source to be 
implanted in silicon.  Common knowledge is the Ion is an atom which has gained 
or lost and electron thus making it a positive or negative ion.  When this Ion 
is implanted into silicon what is the interaction with the valence electrons of 
the ion and silicon that make the implanted region into an n or p type region 
(one with more electrons or holes)? It would be real helpful if you could give 
an example of an implant with the boron ion as well as the arsenic ion with the 
subject of charge carriers so I can get a better feel for what is going on once 
these ions are annealed.
Thanks

Re: How do Ion's implanted into silicon change the area into dopant sites?