Thermal Conductivity and Effusivity Measurement of High Thermal Conductive SiC Single Crystal Using Thermal Microscope

Abstract

Thermal properties of materials at micrometer-scale were quantitatively measured with a thermal microscope, using thermoreflectance and periodic heating. Thermal microscope measures phase lag, which is the delay between the signals of periodic heating laser and the reflectance signals of detecting laser, to calculate the thermal effusivity of the test. In this study, phase lag at an individual point, along a line and within an area on the c plane of highly thermally conductive SiC single crystal (4H-N) was measured to evaluate the reliability of the measurement from such materials. The average value of the measured phase lag was –16.4 ± 0.3deg. The small value of standard deviation suggests thermal properties of highly thermally conductive SiC single crystal can be characterized with a high reliability using a thermal microscope. Furthermore, the thermal effusivity, calculated from the thermal diffusivity using a laser flash technique (JIS R 1611), was 26.1kJ/s^0.5m²K. The calibration curve for high thermal effusivity materials was established using the data of SiC single crystal and calibrants such as Si and Ge.
Thermal effusivities of 29.0 ± 0.5kJ/s^0.5m²K and 28.2 ± 0.6kJ/s^0.5m²K for 4H-C and 6H-C SiC single crystals, respectively, were obtained using the calibration curve. Thermal conductivities of 389W/m·K and 368W/m·K, respectively, were calculated from the measured thermal effusivity data.