Very low energy (<1 keV) B+ ion implantation has been carried out on both crystalline and silicon-preamorphized silicon. The amorphous layer depth was determined using Rutherford backscattering analysis (RBS). The penetration depth and channelling tail of B+ ions into silicon was studied as a function of ion energy (100-2000 eV) and low temperature regrowth/annealing (T < 600° C), using secondary ion mass spectroscopy (SIMS). These studies also involved low energy (40-60 eV) ion beam deposition (IBD) of 10-20 nm isotopic 28Si+ cap layer at room temperature to enable accurate SIMS depth profile measurements to be carried out. The results show the extent of the channelling tails at these low energies and indicate that sub 40 nm p+-n junctions with estimated carrier concentrations as high as 1020 cm-3 can be obtained.