Crystallization of bismuth iron garnet thin films using capacitively coupled oxygen plasmas

It is demonstrated for the first time that amorphous bismuth iron garnet films can be crystallized within capacitively coupled oxygen plasmas at temperatures approximately 100 °C lower than required using conventional thermal annealing. We characterize the plasma optical emissions at high pressures (2 Torr-5 Torr) and high rf powers (500 W-800 W) and show that film crystallization is nevertheless related to thermal conditions generated in the plasma. It is demonstrated that these thermal conditions are related to the concentration of the dominant oxygen species O and O⁺ in the plasma, which, in turn, are a function of the rf power and pressure. The plasma treated garnet Faraday rotation and optical transmission are shown to be comparable with conventional oven or rapid thermal annealing.