Hydrogen was known to passivate Si dangling bonds at the Si/SiO2 interface, but the subsequent arrival of H+ at the interface caused de-passivation of Si-H bonds. First-principles density functional calculations showed that, contrary to convention, de-passivation was not a 2-step process: neutralization of H+ by a Si electron and subsequent formation of an H2 molecule. Instead, it was established that H+ was the only stable charge state at the interface and that H+ reacted directly with Si-H, to form an H2 molecule and a positively charged dangling bond (Pb center). As a result, H-induced interface-trap formation does not depend on the availability of Si electrons.

Defect Generation by Hydrogen at the Si-SiO2 Interface. S.N.Rashkeev, D.M.Fleetwood, R.D.Schrimpf, S.T.Pantelides: Physical Review Letters, 2001, 87[16], 165506 (4pp)