Infrared spectra of hydrogenated lightly doped Czochralski silicon show absorption due to (a) modes of O-i-H-2 centers (binding energy 0.26 eV), and (b) a mode labeled nu(3HH) at 3618 cm(-1) due to H-2 molecules. Annealing produces reversible changes in the equilibrium concentrations of O-i-H-2 and nu(3HH) that reveal a linear anticorrelation. An analysis using a two-center statistical model indicates that the number density of available sites for nu(3HH) centers is 10(22)-10(23) cm(-3) and we propose that the nu(3HH) centers are isolated molecules occupying interstitial lattice sites. The H-2 alignment must be (111) or (110) to account for the infrared activity. [References: 22]
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