Ferromagnetic HfO_2/Si/GaAs interface for spin-polarimetry applications

摘要

In this letter, we present electrical and magnetic characteristics of HfO_2-based metal-oxide-semiconductor capacitors (MOSCAPs), along with the effect of pseudomorphic Si as a passivating interlayer on GaAs(001) grown by molecular beam epitaxy. Ultrathin HfO_2 high-k gate dielectric films (3-15 nm) have been grown on Si/GaAs(001) structures through evaporation of a Hf/HfO_2 target in NO_2 gas. The lowest interface states density D_(it) at Au/HfO_2/Si/GaAs(001) MOS-structures were obtained in the range of (6- 13) × 10~(11) eV~(-1) cm~(-2) after annealing in the 400-500℃ temperature range as a result of HfO_2 crystallization and the Si layer preservation in non-oxidized state on GaAs. HfO_2-based MOSCAPs demonstrated the ferromagnetic properties which were attributed to the presence of both cation and anion vacancies according to the first-principle calculations. Room-temperature ferromagnetism in HfO_2 films allowed us to propose a structure for the ferromagnetic MOS spin-detector.