Figure 1: Anisotropic failure of Fourier theory. | Nature Communications

Figure 1: Anisotropic failure of Fourier theory.

From: Anisotropic failure of Fourier theory in time-domain thermoreflectance experiments

Figure 1

(a) Amplitude of measured in-phase and out-of-phase temperature response of 80 nm Al/Si at room temperature as a function of pump/probe delay time with w0=1.05 and 10.3 μm (circles), and the prediction of an isotropic diffusive model with bulk thermal properties for Si and an Al/Si interface conductance of GA=250 MW m−2 K−1 (lines). Bulk thermal properties for Si cannot explain the magnitude of Tout at w0=1.05 μm; a thermal conductivity of ΛA=105 W m−1 K−1 is required to explain the data with an isotropic diffusive model (b) Amplitude of the measured out-of-phase temperature response at −100 ps delay time and w0=1.05 μm, as function of offset distance between pump and probe beam centres. An anisotropic diffusive thermal model with Λr=80 and Λz=140 W m−1 K−1 (red curve) is in good agreement with the data, while an isotropic value of ΛA=105 W m−1 K−1 (blue curve) over-predicts the amplitude of temperature oscillations away from the centre of the pump beam.

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