Effective electron mobility in Si inversion layers in metal-oxide-semiconductor systems with a high-κ insulator: The role of remote phonon scattering

摘要

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-κ 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_(2)O_(3), AlN, ZrO_(2), HfO_(2), and ZrSiO_(4) for "SiO_(2)-equivalent" thicknesses ranging from 5 to 0.5 nm.