Investigation of hexagonal ferrite substrate and film growth

Hexagonal ferrites with large anisotropy fields can operate close to resonance at mm-wave frequencies. The growth of device-quality hexagonal ferrite films depends on the availability of lattice-matched substrates and optimized film deposition methods. Several potential substrate candidates were identified and characterized. Two promising materials, Ba3(VO4)2and CoGa2O4were chosen for detailed study by LPE growth of hexaferrite films. Under the LPE growth conditions so far investigated, either no film nucleated on the Ba3(VO4)2or the substrates reacted with the melts. LPE layers were successfully grown on CoGa2O4substrates. There was an interdiffused layer at the interface of the hexaferrite film and CoGa2O4substrate. To obtain device-quality films on SrGa12O19substrates (used for comparison), both film and substrate lattice parameters had to be adjusted by chemical substitution.