Thermal diffusivity of surface-microstructured silicon measured by photothermal deflection technique

The thermal diffusivity of surface-microstructured silicon, prepared by cumulative irradiating with femtosecond laser pulses in ambient gas of SF6, was measured at room temperature using laser-induced photothermal deflection technique. The spikes formed on the surface of silicon after irradiation are of elliptic conical shape due to the linearly polarized laser irradiation. The thermal diffusivity of surface-microstructured silicon is sensitive to the orientation of measurements, and decreases by 17.7–29.9% compared with that of unstructured silicon. The experimental results also show that the thermal diffusivity of surface-microstructured silicon decreases with the increasing of the height of spikes.