| AVS 55th International Symposium & Exhibition | |
| Magnetic Interfaces and Nanostructures | Wednesday Sessions |
| Session MI+NC-WeM |
| Session: | Magnetic Thin Films, Nanoparticles and Nanostructures |
| Presenter: | Z. Cai, Northeastern University |
| Authors: | Z. Cai, Northeastern University T.L. Goodrich, Northeastern University Z. Chen, Northeastern University F. Yang, Northeastern University V.G. Harris, Northeastern University K.S. Ziemer, Northeastern University |
| Correspondent: | Click to Email |
Integration of nonreciprocal ferrite microwave devices (e.g. circulators, isolators, phase shifters, etc.) with semiconductor platforms is a necessary to meet the increasing security, usage, and portability demands of civilian and military communication systems by increasing microwave power and by reducing device volume. Barium hexaferrite (BaM, BaFe12O19) is ideal for microwave device applications because of its high resistivity and particularly large uniaxial magnetocrystalline anisotropy (17 kOe) with the easy direction along the c-axis. BaM films with improved ferromagnetic resonance linewidths (< 100 Oe) have been deposited on 6H-SiC by pulsed laser deposition (PLD) through the use of a 10nm single crystalline MgO template grown by molecular beam epitaxy (MBE). Since the improvement in magnetic properties of BaM films is linked to the initial stages of BaM film growth, MBE deposition of high quality BaM has the potential to be an ideal seed layer for thick BaM film deposition by PLD or liquid phase epitaxy (LPE). BaM growth by MBE was carried out using an oxygen plasma source at pressure (<1×10-5 Torr) and solid source Ba and Fe effusion cells at substrate temperature ranging from 300~800ºC. High quality film with strong c-axis aligned normal to the substrate and low coercivity (200 Oe) was achieved at 750 ºC and 2×10-6 Torr with 10nm MBE-grown MgO template. In-situ x-ray photoelectron spectroscopy and reflection high-energy electron diffraction showed stoichiometric chemistry and ordered crystal structure. Ex-situ atomic force microscopy revealed a smooth surface (1.2 nm root-mean-square roughness over a 2 × 2 μm2) and x-ray diffraction patterns showed strong epitaxial growth of c-axis perpendicular to the substrate. Magnetic hysteresis loops confirmed that the easy magnetic axis of the BaM film was aligned perpendicular to the film plane. This is believed to be the first demonstration of oriented, crystalline BaM on SiC by MBE, and has the potential to be a simple and successful method to realize effective integration of BaM with SiC for next-generation microwave device application.