Adsorption-controlled growth of BiFeO3 by MBE and integration with wide band gap semiconductors
Ihlefeld, J.F., W. Tian, Z.K. Liu, W.A. Doolittle, M. Bernhagen, P. Reiche, R. Uecker, Ramamoorthy Ramesh, D.G. Schlom
BiFeO3 thin films have been deposited on (101) DyScO 3, (0001) AlGaN/GaN, and (0001) SiC single crystal substrates by reactive molecular-beam epitaxy in an adsorption-controlled growth regime. This is achieved by supplying a bismuth over-pressure and utilizing the differential vapor pressures between bismuth oxides and BiFeO3 to control stoichiometry. Four-circle x-ray diffraction reveals phase-pure, epitaxial films with rocking curve full width at half maximum values as narrow as 7.2 arc seconds (0.002°). Epitaxial growth of (0001)-oriented BiFeO3 thin films on (0001) GaN, including AlGaN HEMT structures, and (0001) SiC has been realized utilizing intervening epitaxial (111) SrTiO3 / (100) TiO2 buffer layers. The epitaxial BiFeO3 thin films have two in-plane orientations: [112̄0] BiFeO3 || [112̄0] GaN (SiC) plus a twin variant related by a 180° in-plane rotation. This epitaxial integration of the ferroelectric with the highest known polarization, BiFeO3, with wide band gap semiconductors is an important step toward novel field-effect devices.
IEEE International Symposium on Applications of Ferroelectrics
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