Recent advances in monochromatic aberration corrected electron microscopy make it possible to detect the lattice vibration with both high-energy resolution and high spatial resolution. Here, we use sub-10 meV electron energy loss spectroscopy to investigate the local vibrational properties at surface and interface of an amorphous SiO$_2$ (a-SiO$_2$) thin film on Si substrate. We find that each optical mode splits into three sub-modes, i.e., surface mode, bulk mode and interface mode, which can be measured from different locations. The pure surface modes can be measured in the vacuum near the surface, and the pure interface modes are expected to be obtained either at the interface location or in the Si, while inside the SiO$_2$ the measured signal is a mixture of bulk, surface, and interface modes. The bulk mode has the largest vibration energy and surface mode has the lowest. The energy of surface mode is thickness dependent, showing a blue-shift as z-thickness (parallel to fast electron beam) of SiO$_2$ film increases, while the bulk and interface modes have constant vibration energy. The intensity of bulk mode linearly increases with thickness being increased, and it drops steeply to zero near the surface and interface (within a few nanometers). The surface modes decay slowly in the vacuum following a Bessel function. The mechanism of the observed spatially dependent vibration behavior is discussed and quantitatively compared with dielectric response theory analysis. Our nanometer scale measurements of vibrations properties provide useful information about the bonding conditions at the surface and interface and thus may help to design better silicon-based electronic devices via surface and interface treatments
Mechanism of Oxygen Reduction via Chemical Affinity in NiO/SiO2 Interfaces Irradiated with keV Energy Hydrogen and Helium Ions for Heterostructure Fabrication
Probing Temperature at Nanoscale through Thermal Vibration Characterization using Scanning Precession Electron Diffraction
State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Future Material Innovation Center, Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University（上海交通大学）；School of Physics and Electronics, Hunan Key Laboratory of Super Microstructure and Ultrafast Process, State Key Laboratory of Powder Metallurgy, Central South University（中南大学）；Research Center for Scientific Data Hub, Zhejiang Lab（浙江实验室）；School of Physics and Astronomy, Shanghai Jiao Tong University, Key Laboratory for Particle Astrophysics and Cosmology (MOE), SKLPPC（上海交通大学）；School of Mechanical Engineering, Shanghai Jiao Tong University（上海交通大学）
Topology-Driven Vibrations in a Chiral Polar Vortex Lattice
Oak Ridge National Laboratory（橡树岭国家实验室）；Vanderbilt University（范德堡大学）；University of California, Berkeley（加州大学伯克利分校）；University of Virginia（弗吉尼亚大学）；University of Illinois（伊利诺伊大学）；University of Southern California（南加州大学）；Bruker AXS LLC（布鲁克AXS有限责任公司）；Arizona State University（亚利桑那州立大学）；Rice University（莱斯大学）
PySlice: Routine Vibrational Electron Energy Loss Spectroscopy Prediction with Universal Interatomic Potentials
Vanderbilt University（范德堡大学）；Oak Ridge National Laboratory（橡树岭国家实验室）；University of Virginia（弗吉尼亚大学）；University of Washington（华盛顿大学）；Uppsala University（乌普萨拉大学）
