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

LaAlO₃ 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 (ΔV_T/ΔT) is -1.51 mV/K. The electron mobility limited by surface roughness is proportional to E_eff^-0.66 in the electric field of 0.93 MV/cm≪E_eff≪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.