We have investigated the thermal behavior of hydrogen molecules trapped by
multivacancies in crystalline silicon by performing thermal annealing. The
hydrogen molecules had two Raman components with different annealing stages
. Their activation energies for annihilation were 0.7 +/- 0.3 and 0.5 +/- 0
.2eV for the main component and the shoulder, respectively. The former was
attributed to the potential barrier for a hydrogen molecule to escape from
a multivacancy trap, and the latter to move from a metastable site around t
he multivacancy trap to the most stable site. Annealing at 610 degreesC sug
gested that relatively large multivacancies such as V-6 and V-10 are possib
le trapping centers of the hydrogen molecules. (C) 2001 Elsevier Science B.
V. All rights reserved.