Unraveling the electronic structures in different phases of gadolinium sesquioxides performed by electron energy loss spectroscopy
Guo-Jiun Shu,
Sz-Chian Liou,
W. Chun-Hsin Kuo,
Chien-Ting Wu,
Pei-Chieh Wu,
Christopher J. Klingshirn,
Jueinai Kwo,
Minghwei Hong
Affiliations
Guo-Jiun Shu
Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, Taipei 10608, Taiwan
Sz-Chian Liou
Advanced Imaging and Microscopy Laboratory, Maryland NanoCenter, Institute for Research in Electronic and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
W. Chun-Hsin Kuo
Materials Characterization Facility, Texas A&M University, College Station, Texas 77845, USA
Chien-Ting Wu
Materials Analysis Division, Taiwan Semiconductor Research Institute, National Applied Research Laboratories, Hsinchu 300091, Taiwan
Pei-Chieh Wu
Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, Taipei 10608, Taiwan
Christopher J. Klingshirn
Department of Material Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
Jueinai Kwo
Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
Minghwei Hong
Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan
The gadolinium sesquioxide (Gd2O3) with its bandgap of ∼5.4 eV and high dielectric permittivity and refractive index has been used widely in optics, magnetic resonance imaging, and high k dielectrics. Electron energy loss spectroscopy (EELS) reveals spectral features at 13.5 eV and 15 eV, which can be interpreted as surface and volume plasmons, respectively. The unusual surface exciton polariton, with surface resonances associated with excitonic onsets, was also observed at ∼7.5 eV. Because of the differences in electronic structures between the cubic and the monoclinic phases of Gd2O3, it is straightforward to distinguish the two phases using the low-loss regime and O K-edge as a fingerprint. We further successfully performed EELS and electron diffraction to identify the crystalline phase of a single-crystal Gd2O3 film epitaxially grown on a Si(111) substrate.
