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Design and fabrication of the test-structure for measuring thermal properties of CNWs. (a) Deposition of thin-film titanium thermometer on a fused silica substrate. (b) Deposition of aluminium nitride (AlN) as insulating layer. (c) Growth of carbon nanowalls. The titanium thermometer was incorporated into a Wheatstone bridge. The temperature increase, induced by absorption of a laser pulse at a wavelength of 1064 nm, was detected by measuring the unbalanced voltage of the bridge. As the fused silica is transparent at 1064 nm, the radiation coming from the back sideof the test-structure was absorbed by the titanium layer. (d) A cross-sectional SEM image of a CNW layer deposited by expanding beam RF plasma during 90 min at 600 °C. The inset is a top view image (scale bar is 500 nm).
(a) Time-dependent temperature signal of 4300 nm thick CNW layer showing a good agreement between experimental and calculated data. (b)Apparent thermal conductivity of CNW layers at room temperature versus the thickness . Measurements of referring to the porous CNW layers are plotted as black solid circles. Measurements of referring to carbon nanowalls are plotted as red solid squares. The red continuous line is the fit of obtained with Eq. (4) for = 300 Wm−1 K−1 and = 3.6 × 10−8 Km2 W−1. In the plot ( ), contribution of voids in the CNW porous layers was eliminated by using formula (3) derived from the effective medium theory. 24 Uncertainties on and were evaluated to 10% and 15%, respectively.
Thermal resistance / of the CNWs versus the thickness . Experimental data are plotted as red solid circles. They are fitted with Eq. (4) and plotted as a red continuous line with the intrinsic thermal conductivity = 300 Wm−1 K−1 and the boundary resistance = 3.6 × 10−8 Km2 W−1.
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