The formation of hydrogen ͑H͒ related complexes and their effect on boron ͑B͒ dopant were investigated in B-ion implanted and annealed silicon ͑Si͒ substrates treated with a high concentration of H. Isotope shifts by replacement of 10 B with 11 B were observed for some H-related Raman peaks, but not for other peaks. This shows proof of the formation of B-H complexes in which H directly bonds to B in Si. This is an experimental result concerning the formation of B-H complexes with H bonded primarily to B. Electrical resistivity measurements showed that the B acceptors are passivated via the formation of the observed B-H complexes, as well as the well-known passivation center in B-doped Si; namely, the H-B passivation center.

In [1] it was shown how the flavor symmetry A 4 (or S 4 ) can arise if the three fermion generations are taken to live on the fixed points of a specific 2-dimensional orbifold. The flavor symmetry is a remnant of the 6-dimensional Poincaré symmetry, after it is broken down to the 4-dimensional Poincaré symmetry through compactification via orbifolding. This raises the question if there are further non-abelian discrete symmetries that can arise in a similar setup. To this end, we generalize the discussion by considering all possible 2-dimensional orbifolds and the flavor symmetries that arise from them. The symmetries we obtain from these orbifolds are, in addition to S 4 and A 4 , the groups D 3 , D 4 and D 6 ≃ D 3 × Z 2 which are all popular groups for flavored model building.

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