We investigated the formation and annihilation of H-point defect complexes
formed in C-doped Si by heating at high temperatures followed by quenching
in hydrogen gas. Specimens of C-doped Si were sealed in quartz capsules tog
ether with hydrogen (H) gas, at pressure 0.8-1.5 atm at high temperature, a
nd were heated at high temperature for 1 h followed by quenching in water.
We measured their optical absorption spectra at about 7 K with an Fourier t
ransform infrared spectrometer. We observed several optical absorption peak
s due to H-point defect complexes. The optical absorption peaks observed at
2192 and 2203 cm-1 were assigned to the Si-H stretching mode of three hydr
ogen atoms bound to a vacancy (VH3 defect). The formation of the VH4 defect
is due to the reaction between H and the VH3 defect. From isothermal annea
ling experiments, the activation energy for the dissociation of the VH4 def
ect was determined to be about 2.5 eV. (C) 2000 American Institute of Physi
cs. [S0021-8979(00)04021-4].