Fabrication of metal–oxide–semiconductor field-effect transistors using crystalline γ-Al2O3 films as the gate dielectrics

Abstract

Crystalline γ-Al2O3 films were employed as high-κ gate dielectrics in metal–oxide–semiconductor field-effect transistors (MOSFETs) and characterization of these devices was performed. The crystalline dielectric was deposited with thicknesses of 4.0–4.5nm by mixed source molecular beam epitaxy and the capacitance equivalent thicknesses obtained were 2.7–2.9nm. The MOSFETs had exceptionally steep subthreshold slopes (63–67mV∕decade), relatively low negative fixed charge densities (5–7×1012cm−2) and interface state densities (2–3×1011eV−1cm−2). The maximum values of the effective carrier mobilities were 145cm2∕Vs for electrons and 85cm2∕Vs for holes.