Data on two H-related radiation-damage centers (B181, B811) were compared with data on other B-type centers. It was shown that the radiative lifetimes of the luminescence were long; being equal to 28s for the B181 center at 6.5K and equal to 86s for the B811 center at 2K. These values were consistent with the luminescence that arose from excitons which were bound to centers that were iso-electronic with the Si lattice. It was found that the energies of the bound-exciton multiplet states, and their response to magnetic fields, could be precisely fitted when the primary axis of each center was close to a <112> axis of Si. The excitons had spectroscopic binding energies of 0.012 and 0.018eV for the 2 centers. However, vibronic side-bands indicated that relaxations of 0.540eV occurred when the excitons were bound. It was concluded that the centers were examples of defects whose excited states were resonant with the crystal band states, until stabilized by the relaxation. A comparison of the properties of known shallow H-related radiation-damage centers showed that they comprised a unified class of similar defects.

A.S.Kaminskii, E.V.Lavrov, G.Davies, E.C.Lightowlers, A.N.Safonov: Semiconductor Science and Technology, 1996, 11[12], 1796-803