Pulsed photothermal reflectance measurement of the thermal conductivity of sputtered aluminum nitride thin films

We report on measurements of the thermal conductivity of reactively sputtered aluminum nitride (AlN) thin films with different thickness, ranging from $100\mathrm{nm}$ to $1\mu \mathrm{m}$ , on silicon substrates. The measurements were made at room temperature using the pulsed photothermal reflectance technique. The thermal conductivities of the sample are found to be significantly lower than the single-crystal bulk $\mathrm{AlN}$ and increase with an increasing thickness. The thermal resistance at the interface between the $\mathrm{AlN}$ film and the silicon substrate is found to be about $7–8\times {10}^{-8}{\mathrm{m}}^2\mathrm{K}∕\mathrm{W}$ .