Influence of the metallic absorption layer on the quality of thermal conductivity measurements by the transient thermo-reflectance method

This work investigates numerically the influence of a metallic absorption layer on the laser-based measurements of the thermal conductivity of dielectric NOD and semiconductor (Si) electronic materials. The validity of the approach and the obtained results are assessed by comparison with experimental measurements obtained for gold-covered silicon dioxide samples. The results reveal the presence of behaviors associated with thermally thin and thermally thick absorption layers, depending on the ratio between the thickness of the absorption layer and the heat penetration depth. Optimal performance of the transient thermo-reflectance method was found to exist for thicknesses of metal layers falling between the identified thermally thin and thermally thick layers. (C) 2002 Elsevier Science Ltd. All rights reserved.