Polarization Selectivity of Aloof-Beam Electron Energy-Loss Spectroscopy in One-Dimensional ZnO Nanorods
Polarization Selectivity of Aloof-Beam Electron Energy-Loss Spectroscopy in One-Dimensional ZnO Nanorods
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DOI：
10.1103/physrevapplied.16.054009
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发表时间：
2021-10
影响因子：
4.6
通讯作者：
Yao-Wen Yeh;Sobhit Singh;D. Vanderbilt;P. Batson
中科院分区：
文献类型：
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作者：
Yao-Wen Yeh;Sobhit Singh;D. Vanderbilt;P. Batson
利用扫描透射电子显微镜（STEM）对纤锌矿氧化锌纳米棒的电子性质进行了表征。纤锌矿结构的面内（13.0 eV）和面外（11.2 eV）方向的两个关键的晶体取向区分特定的过渡进行检查的第一性原理密度泛函理论计算。我们注意到在3.4 eV附近的直接带隙跃迁的发病一定程度的取向依赖性。我们表明，可以实现良好的极化选择性，通过将电子探针在不同的位置周围的试样增加的影响参数，同时保持束试样的方向固定。所观察到的结果定性地阐明在显微镜中使用的快速电子（60千伏）所产生的垂直电场。事实上，良好的偏振选择性可以实现远光束EELS，而不需要样品重定向是一个有吸引力的方面，从表征方法的角度来看，在STEM-EELS社区。
Orientation dependent electronic properties of wurtzite zinc oxide nanorods are characterized by aloof beam electron energy-loss spectroscopy (EELS) carried out in a scanning transmission electron microscope (STEM). The two key crystal orientation differentiating transitions specific to the in-plane (13.0 eV) and out-of-plane (11.2 eV) directions with respect to the wurtzite structure are examined by first principles density-functional theory calculations. We note some degree of orientation dependence at the onset of direct band gap transition near 3.4 eV. We demonstrate that good polarization selectivity can be achieved by placing the electron probe at different locations around the specimen with increasing impact parameter while keeping the beam-specimen orientation fixed. The observed results are qualitatively elucidated in terms of the perpendicular electric fields generated by the fast electron (60 kV) used in the microscope. The fact that good polarization selectivity can be achieved by aloof beam EELS without the requirement of sample reorientation is an attractive aspect from the characterization method point of view in the STEM-EELS community.