Fig. 2: Temperature map and ITR characterization under AlN-to-SiC heat flow.

a, Low-magnification high-angle annular dark-field STEM image (left) and atomic-resolution image (right) of the AlN–SiC interface. Scale bars, 500 nm (left), 2 nm (right). b, Linear plots of the logarithm of the ratio between loss and gain scattering as a function of excitation energy. Colour-coded spectra correspond to the acquisition positions marked by the corresponding coloured dots in a. c, Temperature map of the area marked by the white dashed box in a and the temperature profiles of each row. d, Corresponding isotherm diagram and temperature gradient field (black arrows), superimposed on the high-angle annular dark-field image to visualize thermal transport directionality. e, Interface-adjacent temperature profiles under varying heating currents from another sample (see Supplementary Fig. 1a). Linear fits to bulk regions (coloured text) yield temperature gradients, whereas the interface temperature drop (ΔT) is denoted by black text. Coloured shaded areas represent the standard deviation of the mean from several data points. f, Relative ITR is quantified by the interface characteristic length, derived from the relationship between the interface temperature drop and the bulk temperature gradient in AlN and SiC, respectively.