Fabrication and characterization of Bi-substituted yttrium iron garnet films by pulsed laser deposition

Abstract

We have systematically investigated the effects of processing parameters, including various oxygen pressures (Po2) ranging from 200 to 1000 m Torr and substrate temperatures (Ts) ranging from 500 to 750°C, on the characteristics of Bi-substituted yttrium iron garnet (Bi:YIG) films grown on (111) gadolinium gallium gamet (GGG) substrates. Bi: YIG films were grown using a pulsed laser deposition method with an ArF excimer laser (λ=193 nm). Although the compositions of all the Bi:YIG films grown at the constant Ts of 600°C were close to the target composition irrespective of Po2, the Bi contents were slightly increased with increasing Po2, which was consistent with the variation in Faraday rotation angles (θF). In addition, the crystallinity of the Bi:YIG films was deteriorated with increasing Po2, and their grains became irregular. At Ts above 700°C, Bi-deficient yttrium iron garnet films were grown. Consequently, high quality epitaxial Bi:YIG films exhibiting Faraday rotation angles of −1.0≈−1.5 degree/μm were successfully grown at the substrate temperatures in the range of 500–650°C when the Po2 of 200 mTorr was used.