Degradation mechanisms of electron mobility in metal-oxide-semiconductor field-effect transistors with LaAlO3 gate dielectric

Abstract

LaAlO 3 is a promising candidate of gate dielectric for future very large scale integration devices. In this work, metal-oxide-semiconductor capacitors and transistors with LaAlO3 gate dielectric were fabricated and the electron mobility degradation mechanisms were studied. The LaAlO3 films were deposited by radio frequency magnetron sputtering. The LaAlO3 films were examined by x-ray diffraction, secondary ion mass spectroscopy, and x-ray photoelectron spectroscopy. The temperature dependence of metal-oxide-semiconductor field-effect transistors characteristics was studied from 11 K to 400 K. The rate of threshold voltage change with temperature (ΔVT/ΔT) is −1.51 mV/K. The electron mobility limited by surface roughness is proportional to Eeff−0.66 in the electric field of 0.93 MV/cm<Eeff<2.64 MV/cm at 300 K and the phonon scattering is proportional to T−5.6 between 300 and 400 K. Soft optical phonon scattering was used to explain the extra source of phonon scattering in LaAlO3-gated n-channel metal-oxide-semiconductor field-effect transistors.