Pshenay-Severin D A, Adamov R B, Vinnichenko M Ya, Moldavskaya M D, Shalygin V A
Institute of Electronics and Telecommunications, Peter the Great St. Petersburg Polytechnic University, 29 Polytechnicheskaya str., St. Petersburg 195251, Russia.
Ioffe Institute, 26 Politechnicheskaya str., St. Petersburg 194021, Russia.
J Phys Condens Matter. 2023 Mar 1;35(17). doi: 10.1088/1361-648X/acbb4b.
Temperature evolution of the high-resolution far-infrared transmission spectra of 6H-SiC single crystal slab is experimentally examined in a temperature range of 5-320 K. Temperature dependences of the phonon lifetimes for long-lived phonons, namely the IR active folded transverse acoustic (FTA) phonon doublet, are determined. These dependences are interpreted in the framework of a theoretical model developed using first principle anharmonic lattice dynamics. It is shown that three-phonon anharmonic processes dominate in the FTA phonon decay at temperatures above 160 K resulting in a rapid decrease of the phonon lifetimes with increasing temperature. Contribution of four-phonon anharmonic processes is negligibly small at temperatures below 320 K.
在5 - 320 K的温度范围内，通过实验研究了6H - SiC单晶片高分辨率远红外透射光谱的温度演变。确定了长寿命声子（即红外活性折叠横向声学（FTA）声子双峰）的声子寿命与温度的关系。这些关系在使用第一原理非谐晶格动力学开发的理论模型框架内得到解释。结果表明，在温度高于160 K时，三声子非谐过程在FTA声子衰减中占主导地位，导致声子寿命随温度升高而迅速降低。在温度低于320 K时，四声子非谐过程的贡献小到可以忽略不计。
