The aim of this work is to investigate the correlation between the electrical and structural properties of Si samples doped with B, Ga and B+Ga. The samples have been prepared by implanting the selected dopants into a Si layer previously amorphized by Si ion implantation. A thermal treatment at 550 o C has been used to recover the crystalline quality and to activate the implanted dopants. The lattice location of the implanted impurities has been determined by means of accurate channelling measurements, using standard RBS techniques and selected nuclear reactions for Ga and B, respectively. In particular the 1 1 B(p,α) 8 Be * nuclear reaction has been used to determine the B lattice location at 0.7 MeV proton energy. Analyses have been performed using an HVEE coaxial Cockroft-Walton singletron accelerator with a maximum terminal voltage of 3.5 MV and excellent energy stability over the entire accelerating voltage range, recently installed at the department of Physics (University of Catania). Hall mobility and carrier fluence have been measured and the latter has been compared to the B and Ga substitutional fluence.