Anisotropy and thermal properties in GeTe semiconductor by Raman analysis

作者：Yang, Shuai; Sui, Fengrui; Liu, Yucheng; Qi, Ruijuan^*; Feng, Xiaoyu; Dong, Shangwei; Yang, Pingxiong; Yue, Fangyu^*

来源：Nanoscale, 2023, 15(32): 13297-13303.

DOI：10.1039/d3nr02678g

• THERMOELECTRIC-MATERIALS
• PHASE-TRANSITION
• HIGH-PERFORMANCE
• SCATTERING
• PHONONS
• DENSITY
• ORDER

Low-symmetric GeTe semiconductors have attracted wide-ranging attention due to their excellent optical and thermal properties, but only a few research studies are available on their in-plane optical anisotropic nature that is crucial for their applications in optoelectronic and thermoelectric devices. Here, we investigate the optical interactions of anisotropy in GeTe using polarization-resolved Raman spectroscopy and first-principles calculations. After determining both armchair and zigzag directions in GeTe crystals by transmission electron microscopy, we found that the Raman intensity of the two main vibrational modes had a strong in-plane anisotropic nature; the one at & SIM;88.1 cm(-1) can be used to determine the crystal orientation, and the other at & SIM;124.6 cm(-1) can reveal a series of temperature-dependent phase transitions. These results provide a general approach for the investigation of the anisotropy of light-matter interactions in low-symmetric layered materials, benefiting the design and application of optoelectronic, anisotropic thermoelectric, and phase-transition memory devices based on bulk GeTe.