Numerical calculation of thermoreflectance coefficient of c-Si for wavelengths of 200-800 nm and temperatures of 300-500 K

In this paper, the thermoreflectance (TR) coefficient of c-Si is numerically calculated over the wavelength range of 200-800 nm and the temperature range of 300-500 K using a complex permittivity model that considers interband transitions and free carriers. The calculated results are in good agreement with literature values, and it is found that the temperature dependence of the TR coefficient is almost negligible at wavelengths above 500 nm. On the other hand, in the wavelength range of 200-500 nm, the TR coefficient depends strongly on the wavelength, and the temperature stability also changes significantly depending on the wavelength. This suggests that the wavelength of the probe light for TR measurement should be appropriately selected to realize high sensitivity and temperature stability, considering the constraints of the optical system and the temperature range of the sample.