  Gate-pulse-induced recombination, known as the charge pumping (CP), is a
fundamental carrier recombination process, and has been utilized as a method
for analyzing electrical properties of defects (or dangling bonds) at the
transistor interfaces, which is now recognized to be well-matured and
conventional. Nevertheless, neither the origin (the bonding configuration) of
the defects responsible for the CP, nor their detailed recombination sequence
has been clarified yet for Si metal-oxide-semiconductor (MOS) interfaces. In
order to address these problems, we investigated the CP under spin resonance
conditions at temperatures ranging from 27 to 300 K in Si(100) n-type MOS
transistors. We obtained evidence that Pb0 and E' centers, the two major
dangling bonds at (and near) the Si(100) interface, participate in the CP
recombination process. We also show that the spin-dependent CP process is
explained by the formation of electron-electron spin pairs, which in turn
reveals that the CP via Pb0 and E' centers is inherently a two-electron
process.
