Thermal Conductivity of Chalcogenide As2S3 Thin Films

In order to investigate the photo-induced thermal property changes in chalcogenide thin films, amorphous As2S3 thin film samples, whose thicknesses are 0.5, 1.0, 2.0, and 4.0μm, were prepared on silicon wafers by thermal evaporation. Their thermal conductivity was measured by the 3ω method between room temperature and 100 ◦C. These measurements were repeated after the illumination of an Ar+ laser beam whose photon energy is consistent with the bandgap energy of As2S3, and repeated again for annealed films at 180 ◦C for 1 h. The result shows that the thermal conductivities of fresh films were 0.14 to 0.27 W·m−1 ·K−1; however, the values increase to 0.28–0.47 W·m−1 ·K−1 after illumination of the sample and decrease to 0.19–0.42 W· m−1 · K−1 after annealing of the sample. These changes can be explained by the change in microstructure produced from the photo-darkening and thermal annealing.