Zawadzka Natalia, Kipczak Łucja, Woźniak Tomasz, Olkowska-Pucko Katarzyna, Grzeszczyk Magdalena, Babiński Adam, Molas Maciej R
Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-093 Warsaw, Poland.
Department of Semiconductor Materials Engineering, Wrocław University of Science and Technology, 50-370 Wrocław, Poland.
Nanomaterials (Basel). 2021 Nov 18;11(11):3109. doi: 10.3390/nano11113109.
The optical response of bulk germanium sulfide (GeS) is investigated systematically using different polarization-resolved experimental techniques, such as photoluminescence (PL), reflectance contrast (RC), and Raman scattering (RS). It is shown that while the low-temperature ( = 5 K) optical band-gap absorption is governed by a single resonance related to the neutral exciton, the corresponding emission is dominated by the disorder/impurity- and/or phonon-assisted recombination processes. Both the RC and PL spectra are found to be linearly polarized along the armchair direction. The measured RS spectra over a broad range from 5 to 300 K consist of six Raman peaks identified with the help of Density Functional Theory (DFT) calculations: Ag1, Ag2, Ag3, Ag4, B1g1, and B1g2, which polarization properties are studied under four different excitation energies. We found that the polarization orientations of the Ag2 and Ag4 modes under specific excitation energy can be useful tools to determine the GeS crystallographic directions: armchair and zigzag.
使用不同的偏振分辨实验技术，如光致发光（PL）、反射率对比度（RC）和拉曼散射（RS），系统地研究了块状硫化锗（GeS）的光学响应。结果表明，虽然低温（ = 5 K）光学带隙吸收由与中性激子相关的单一共振控制，但相应的发射则由无序/杂质和/或声子辅助复合过程主导。发现RC和PL光谱均沿扶手椅方向线性偏振。在5至300 K的宽范围内测量的RS光谱由六个拉曼峰组成，这些峰借助密度泛函理论（DFT）计算得以识别：Ag1、Ag2、Ag3、Ag4、B1g1和B1g2，并在四种不同的激发能量下研究了它们的偏振特性。我们发现，在特定激发能量下，Ag2和Ag4模式的偏振方向可作为确定GeS晶体学方向（扶手椅和锯齿形）的有用工具。
