Measurement of thermal conductivity of chalcogenide As/sub 2/S/sub 3/ thin films using 3-omega method

Photo-induced modifications in chalcogenide films include changes in density, hardness, rheological properties, chemical reactivity, electrical and optical properties, therefore the chalcogenide films have been extensively studied recently, partly as an interesting subject for fundamental research in the field of disordered solids and partly due to potential applications in opto-electronics such as photo-resists, optical memories, opto-electronic circuits, etc. However, the thermal properties were not widely investigated compared to the optical and electrical properties. In this study, amorphous As/sub 2/S/sub 3/ thin film samples, whose thicknesses are 0.5 /spl mu/m, 1.0 /spl mu/m, 2.0 /spl mu/m, and 4.0 /spl mu/m, were prepared on silicon waters by the thermal evaporation, and their thermal conductivity was measured by a 3/spl omega/ method between room temperature and 100/spl deg/C. These measurements were repeated after the illumination of A/sup +/+ laser beam whose photon energy is consistent with the band energy gap of As/sub 2/S/sub 3/, and continued for the annealed films in 180/spl deg/C for one hour. The result shows that the thermal conductivities of fresh films were 0.14 /spl sim/ 0.27 W/sup -1-1/1, however increase to 0.28 /spl sim/ 0.47 W/sup -1-1/1 after the illumination of light on the sample and decrease 0.19 /spl sim/ 0.42 W/sup -1-1/1 after annealing of the sample. These changes were explained by the change of microstructure produced from the photo-darkening and thermal annealing.