Epitaxial growth of 100-μm thick M-type hexaferrite crystals on wide bandgap semiconductor GaN/Al2O3 substrates

Thick barium hexaferrite BaFe12O19 (BaM) films having thicknesses of ∼100 μm were epitaxially grown on GaN/Al2O3 substrates from a molten-salt solution by vaporizing the solvent. X-ray diffraction measurement verified the growth of BaM (001) textured growth of thick films. Saturation magnetization, 4πMs, was measured for as-grown films to be 4.6 ± 0.2 kG and ferromagnetic resonance measurements revealed a microwave linewidth of ∼100 Oe at X-band. Scanning electron microscopy indicated clear hexagonal crystals distributed on the semiconductor substrate. These results demonstrate feasibility of growing M-type hexaferrite crystal films on wide bandgap semiconductor substrates by using a simple powder melting method. It also presents a potential pathway for the integration of ferrite microwave passive devices with active semiconductor circuit elements creating system-on-a-wafer architectures.