Thermal conductivity characterization of skutterudite thin films

Experimental results on the temperature dependent cross-plane thermal conductivity of skutterudite thin films are presented. The films examined include IrSb/sub 3/ (175 nm) and CoSb/sub 3/ (110 nm) single layers, an Ir/sub 0.5/Co/sub 0.5/Sb/sub 3/ alloy film (150 nm), and an IrSb/sub 3//CoSb/sub 3/ superlattice (6 nm period) that are grown by pulsed laser deposition. A differential 3/spl omega/ method is used to measure the cross-plane thermal conductivity of these films from 80 K to 300 K. The experimental results show a significant reduction in their thermal conductivity values compared to those of their corresponding bulk samples reported in literature, with the largest reduction observed in the alloy and the superlattice samples. These data suggest that the phonons carrying heat in bulk superlattices have long mean free path. The thermal conductivity of the alloy and the superlattice thin film samples are comparable to some filled skutterudites.