Due to the similar atom arrangement with black phosphorus, black arsenic also has obvious Raman anisotropy at both the base and cross planes. However, the polarization characteristics of black arsenic have been rarely reported so far with most relevant studies devoted to the base plane. Here, to compensate for the blank of the anisotropy in cross plane, we implemented a systematical angle‐resolved polarized Raman measurement on both planes of layered black arsenic and observed that the Raman intensity ratios (Ixx : Iyy : Izz) of optical phonons and modes along different axes are 1:4.8:2.76 and 6.9:1:5.7, respectively. Based on the definition of Raman intensity, we abstracted integral Raman tensors of black arsenic. In addition, according to density functional theory, it can be affirmed that the Raman anisotropy of Ag mode is sourced from the anisotropy of differential polarizability along different crystal axes.

Raman tensors, one of the basic physical properties of M o S 2 , are rarely reported. Here, angle-resolved polarized Raman scatterings on basal and cross planes of layered M o S 2 were carried out using the geometry configuration of parallel polarization, and the Raman tensors of three optical vibration modes were systematically studied. As a polar vibration mode, the differential polarizability of the A 1 g mode corresponding to the Raman tensor along the c direction is larger than that along the a direction. In addition, it is also larger than that formed by E 2 g and E 1 g modes. All the experimental results above are beneficial to the understanding of inelastic light-scattering process of M o S 2 .

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Weyl semimetal Td-WTe 2 has attracted extensive attention due to its abundant physical properties. Further study on Td-WTe 2 crystal structure is helpful for its understanding and modification in application. In this article, a method for studying crystal symmetry based on Raman tensor is proposed. Specifically, it analyzed the anisotropy of the material structure by the angle-resolved polarized Raman spectroscopy and discussed the Raman selection rules and the physical image of the Raman tensor matrix element in depth, which filled in the deficiency of information on Raman tensor elements obtained simply by experiments. According to the study and discussion, the basal and cross plane of Td-WTe 2 crystal show incompletely consistent polarization dependence of Raman scattering intensity. Combined with theoretical calculations and angle-resolved Raman spectrum experiments, the corresponding Raman tensor elements of each vibration mode are obtained. The dominant vibration orientation of each mode depends on the differential polarizability corresponding to the Raman tensor element. For the comparison of shrinkage degrees, the mode with larger shrinkage degree tends to vibrate along the c-axis. The results provide a new way for studying the Raman tensor of other transition metal chalcogenides and offers a noble direction for the application of anisotropic thin materials.

Although the dispute remains, the N substitution for the lattice O (NO) in zinc oxide (ZnO) demonstrates the promising future in achieving the p-type ZnO-based semiconductor. In this context, a highly crystallized N-doped ZnO (ZnO:N) film is fabricated with ultralow defect density. Based on the synchrotron radiation X-ray absorption near-edge structure (XANES) and low-temperature photoluminescence (PL) spectra combined with first-principles calculations, the results demonstrate that the majority of N ions locate stably at the lattice O site to succeeding the N substitution for lattice O as the NO defects. A prototype LED device is built based on the homojunction of ZnO:N film and ZnO:Ga wafer with good electroluminescence performance. These important findings provide a rewarding avenue to the p-type ZnO semiconductor design and device fabrication, and demonstrate a prevailing guidance on the materials design and development as well.