Molecular-beam-deposited yttrium-oxide dielectrics in aluminum-gated metal–oxide–semiconductor field-effect transistors: Effective electron mobility

We report on high effective mobilities in yttrium-oxide-based n-channel metal–oxide–semiconductor field-effect transistors (MOSFETs) with aluminum gates. The yttrium oxide was grown in ultrahigh vacuum using a reactive atomic-beam-deposition system. Medium-energy ion-scattering studies indicate an oxide with an approximate composition of Y2O3 on top of a thin layer of interfacial SiO2. The thickness of this interfacial oxide as well as the effective mobility are found to be dependent on the postgrowth anneal conditions. Optimum conditions result in mobilities approaching that of SiO2-based MOSFETs at higher fields with peak mobilities at approximately 210 cm2/V s.