A radio-frequency probe was used to monitor changes in the charge-carrier recombination centres, at a SiO2/Si interface, by monitoring the steady-state photo-generated carrier concentration in Si. A Si surface which was covered with 20nm of thermal oxide was exposed to gaseous molecular H at temperatures of between 135 and 300C. The reaction was found to obey a non-exponential rate law that could be described by a cluster of rate-constants; governed by a Gaussian distribution of activation energies. At high temperatures, the predominant reaction was that of Pb centres; with a rate law that was consistent with that previously deduced using electron paramagnetic resonance techniques. At low temperatures, the reaction was dominated by the passivation of a carrier recombination center with a much lower activation energy. This new species comprised some 25% of the total recombination center concentration at the Si/SiO2 interface. Almost 20% of the recombination centres could not be passivated by H2.

Rate Constants for the Reaction of H2 with Defects at the SiO2/Si(111) Interface L.Gheorghita, E.Ogryzlo: Journal of Applied Physics, 2000, 87[11], 7999-8004