中文摘要：

对6H—SiC单晶体材料进行了从80到320K的低温变温拉曼光谱测量，从实验得到的谱图上指认了部分6H—SiC的折叠拉曼峰，重点利用三声子模型和四声子模型分析了A-（LO）光学声子模峰位和线宽在低温下随温度的变化特性。实验发现，随着温度降低，LO声子模谱峰中心向高波数移动，线宽减小；同时发现当温度低于160K时，无论是谱峰中心位置还是线宽的变化都趋于平缓，这是在常温和高温下观察不到的，说明在160K以下时At（LO）谱线线宽是由声子本身的性质决定，温度对线宽的影响几乎可忽略；理论拟合表明，四声子模型更能与实验数据相符，三次、四次非谐振动共同作用，前者是主要过程；温度越低，A1（LO）光学声子寿命越长，这是由于原子热运动的剧烈程度随温度降低而下降，声子弛豫减弱。

英文摘要：

Variable temperature method was lent for low temperature Raman study on bulk monocrystal 6H-SiC in the temperature range from 80 to 320 K. Some Raman folding modes of 6H-SiC were assigned in the spectrum. The peak position and line width of optical phonon A1 （LO） versus temperature mainly below RT was focused on by 3-phonon and 4-phonon models. The result showed that as the temperature decreased the line width decreased, while the peak position shifted to high wave number. It was found that as the temperature varied below 160 K, the change in peak position and line width was little, different from it was at RT, revealing that the line type of A1 （LO） mode was mainly decided by the phonon characteristics and the effect of temperature could be ignored when it was below 160 K. It was showed that 4-phonon model was closer to the experiment data for fitting. Both the third and forth anharmonic vibration contributed to the spectrum, while the former was the main process. Moreover, the phonon lifetime became longer when the temperature fell because of the decrease in the atomic thermal motion.