Optical absorption spectra, and the annealing behaviour of H plus point-defect complexes in C-doped samples following hydrogenation, were investigated. Specimens of C-doped (1.7 x 1017/cm3) material were sealed into quartz capsules together with H2 gas and were annealed at high temperatures for 1h before quenching in water. The optical absorption spectra were measured at about 7K using Fourier-transform infra-red spectrometry. The VH4 defect was almost annealed out at 600C. The formation energy of this defect in C-doped material was estimated, from the quenching-temperature dependence of the 2223/cm peak, to be about 3.2eV. The 2192 and 2203/cm peaks were attributed to the VH3 defect. This captured an H atom during annealing to become VH4. After annealing at 700C, absorption peaks were observed at 2093 and 2086/cm. These were attributed to Si-H stretching vibrations of H on the internal surfaces of voids. It was deduced that vacancies were introduced into C-doped material at high temperatures, although it was known that C introduced interstitials at high temperatures.

Annealing Behavior of Hydrogen-Defect Complexes in Carbon-Doped Si Quenched in Hydrogen Atmosphere N.Fukata, M.Suezawa: Journal of Applied Physics, 2000, 87[12], 8361-7