Recent advances in monochromatic aberration corrected electron microscopy make it possible to detect the lattice vibrations with both high-energy resolution and high spatial resolution. Here, we use sub-10 meV electro...Recent advances in monochromatic aberration corrected electron microscopy make it possible to detect the lattice vibrations 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 of the SiO_2/Si surface and interface. The energy of the surface mode is thickness dependent, showing a blue shift as z-thickness(parallel to the fast electron beam)of SiO_2 film increases, while the energy of the bulk mode and the interface mode keeps constant. The intensity of the surface mode is well-described by a Bessel function of the second kind. The mechanism of the observed spatially dependent vibrational behavior is discussed and compared with dielectric response theory analysis. Our nanometer scale measurements provide useful information on the bonding conditions at the surface and interface.展开更多
基金Supported by the National Key R&D Program of China under Grant No 2016YFA0300804the National Natural Science Foundation of China under Grant Nos 51502007 and 51672007+2 种基金the National Equipment Program of China under Grant No ZDYZ2015-1the National Program for Thousand Young Talents of Chinathe ‘2011 Program’ Peking-Tsinghua-IOP Collaborative Innovation Center of Quantum Matter
文摘Recent advances in monochromatic aberration corrected electron microscopy make it possible to detect the lattice vibrations 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 of the SiO_2/Si surface and interface. The energy of the surface mode is thickness dependent, showing a blue shift as z-thickness(parallel to the fast electron beam)of SiO_2 film increases, while the energy of the bulk mode and the interface mode keeps constant. The intensity of the surface mode is well-described by a Bessel function of the second kind. The mechanism of the observed spatially dependent vibrational behavior is discussed and compared with dielectric response theory analysis. Our nanometer scale measurements provide useful information on the bonding conditions at the surface and interface.
