Degradation of oxide-passivated boron-diffused silicon

摘要

Recombination in oxide-passivated boron-diffused silicon is found to increase severely at room temperature. The degradation reaction leads to a 45 fold increase in emitter recombination that saturates in ～120 days, irrespective of whether the samples received a forming-gas anneal. The degradation was also examined for diffusions stored at 50, 75, and 100 ℃. The results indicate that the degradation follows a second-order reaction where the time constant of one component of the reaction is 10-40 times shorter than the other, and where the activation energy of the fast reaction is 0.19 ±0.05 eV. Subsequent to degradation, annealing in air reduces the recombination with increasing anneal temperature saturating at ～300 ℃ to a value that is about four times higher than the predegradation value. A likely cause of this degradation is a reaction of atomic hydrogen at the silicon-oxide-silicon interface.