We studied point defects, vacancies (V), and self-interstitials (I), formed
by room-temperature electron irradiation of hydrogenated Si via the observ
ation of the optical-absorption spectra due to complexes formed of hydrogen
and paint defects. The formation of H-2*, a metastable state of H-2 in Si,
was also studied. Specimens were n-type, p-type, and high-purity Si crysta
ls. They were doped with hydrogen (H) by annealing at 1300 degreesC in H-2
gas followed by quenching. Then they were irradiated with 3 MV electrons at
room temperature. We measured their optical-absorption spectra by a Fourie
r-transform infrared spectrometer at about 7 K. Many optical-absorption pea
ks were observed. Among them, 1987 and 1990 cm(-1) peaks were weak in B-dop
ed specimens and the 2122 cm(-1) peak was weak in P-doped specimens. These
results support the hypothesis that the 1987 and 1990 cm(-1) peaks and the
7122 cm(-1) peak are due to complexes including I and V, respectively. The
H-2* concentration does not show good correlations with the concentrations
of V and I. We hypothesize that H-2* is formed from the interaction between
an H-2 and a Frenkel pair.