The high dielectric constant of insulators currently investigated as alternatives to SiO_2 in metal-oxide-semiconductor structures is
due to their large ionic polarizability. This is usually accompanied
by the presence of soft optical phonons. We show that the long-range dipole field associated with the interface excitations resulting from these modes and from their coupling with surface plasmons, while small in the case of SiO_2, for most high-$\kappa$ materials causes a reduction of the
effective electron mobility in the inversion layer of the Si substrate.
We study the dispersion of the interfacial coupled phonon-plasmon modes,
their electron-scattering strength, and their effect on the electron
mobility for Si-gate structures employing films of SiO_2, Al_2O_3, AlN, ZrO_2, HfO_2, and ZrSiO_4 for `SiO_2-equivalent' thicknesses ranging from 5 nm to 0.5 nm.
By: Massimo. V. Fischetti, Deborah A. Neumayer, Eduard A. Cartier
Published in: RC22092 in 2001
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