Effect of hydrogen on shallow dopants in crystalline silicon

摘要

Passivation of shallow impurities by H has been attributed to Hhyphen;impurity pairing in bothphyphen;type andnhyphen;type Si. We show that existing interpretations of data were based on contradictory assumptions and that a coherent interpretation of all the data can only be obtained if one assumes that diffusing H has a donor level in the gap. A novel interpretation emerges: Inphyphen;type material, passivation is due to directcompensation, so that pairing is a consequence, not a cause of passivation; innhyphen;type material, passivation is indeed due to pairing, but is suppressed by H2formation and possibly other reactions. Several predictions are made and new experiments are proposed as tests.