中文摘要：

低温条件下碳化硅等半导体材料热导率的实验研究极少,数据匮乏,无法满足理论模型的优化需求。现有实验测量以接触式的稳态法导热系数测量为主,实验误差大,且低温测量成本过高。本文通过常规飞秒激光抽运探测热反射法与低温系统的有机结合,完成了4~300 K低温条件下单晶碳化硅热导率的测试及其随温度的变化规律,研究表明单晶碳化硅热导率在100 K左右存在极大值,温度低于100 K时其热导率与温度呈正相关,温度高于100 K时其热导率与温度呈负相关。极值点的位置与理论值的偏差可能是由于样品电子浓度、缺陷分布等因素影响。

英文摘要：

There are very limited experimental researches on the thermal conductivity of semiconductors like SiC at low temperatures.Thus,this cannot meet the needs of theoretical model optimization due to the scarce data.The existing experimental measurements are mainly based on the steady state method,which is a contact method with large experimental errors and prohibitive costs.In this paper,via the organic integration of the time-domain thermorenectance and cryogenic system,we measured the thermal conductivity of a single crystal silicon carbide sample under low temperatures ranging from 4 K to 300 K.The result shows that the thermal conductivity of SiC possesses a peak value at about 100 K.When the temperature is lower than 100 K,the thermal conductivity demonstrates a positive correlation with temperature.However,when the temperature is higher than 100 K,there is a negative correlation between the thermal conductivity and the temperature.The deviation of the experimental peak value positions of the thermal conductivities from the theoretically predicted value could be resulted by factors such as electron-doping and different distributions of defects.