Characterization of Laser-Assisted Pulseid Laser Deiposited BaFe12O19

Abstract

ABSTRACTHigh quality, epitaxial barium hexaferrite (BaFe12O19) thin films have been deposited by pulsed laser deposition (PLD) onto basal plane sapphire at substrate temperatures of 900°C in 400 mTorr of oxygen. Thin films (< 500 nm) were smooth while thick films (> 1000 nm) had rough, polycrystalline surfaces and “soot-like” appearances. The integration of ferrite films with semiconductors will require thick films (< 70 μm) and low substrate processing temperatures (≤ 600°C). Films deposited at 600°C were mostly amorphous with the presence of some crystalline, non-hexaferrite material. In an effort to improve the quality of barium hexaferrite fihns, we have investigated the effects of excimer-laser-assisted PLD (LAPLD) on the growth of BaFe12O19. During the deposition, the substrate was illuminated with the output of a second pulsed excimer laser (KrF) weakly focused to an energy of 10 to 130 mJ/cm2. The output of the second laser was synchronized such that the delay between the vaporization laser and the annealing laser was 0 to 1 ms. The X-ray diffraction analysis of LAPLD films deposited at 600°C with an annealing fluence of 50 mJ/cm2 indicated that the films were a crystalline mixture of hexaferrite and non-hexaferrite phases. Both phases exhibited a preferred orientation characterized by narrow x-ray rocking curve widths (FWHM ∼ 1°). Magnetic properties (magnetic moment, saturation magnetization and coercive field) detennined from a vibrating sample magnetometer (VSM) also confirmed the presence of oriented hexaferrite material in the laser annealed samples. These results show clear advantages of LAPLD for improved structural and magnetic properties of BaFe12O19 deposited at substrate temperatures compatible with semiconducting materials.