Preparation and characterization of ferromagnetic DO3-phase Fe3Si thin films on silicon-on-insulator substrates for Si-based spin-electronic device applications

Abstract

The authors developed a preparation technique of stoichiometric and off-stoichiometric ferromagnetic Fe3+δSi1−δ thin films with a DO3 phase structure using silicon-on-insulator (SOI) substrates. Ferromagnetic Fe3+δSi1−δ films were formed by thermally activated silicidation reaction between an ultrathin SOI layer and a Fe layer deposited on it, induced by rapid thermal annealing. Their chemical composition was precisely controlled by the relative thickness ratio of the SOI and Fe layers, and highly oriented DO3-phase polycrystalline Fe3+δSi1−δ films were obtained with annealing temperature ranging from 620 to 780°C. The Fe3+δSi1−δ films exhibited ferromagnetic nature with the Curie temperature much higher than room temperature.