| dc.description.abstract | Thermoelectric materials have attracted great attention in recent years due to sharp increase of energy consumption and environmental protection purpose. Thermoelectric (TE) devices which have shrinking dimensions and high output efficiencies are developed with the advance of materials science and technology. CoSb3 thin film, the eco-friendly medium-temperature TE material, is chosen as the material in this study. CoSb3 thin films with a thickness of 300 nm were deposited on SiO2/Si substrate by radio-frequency (RF) magnetron sputtering method. There were two types of testing samples which were single CoSb3 layer and Cu/Ti/CoSb3 respectively, and Ti acted as the adhesion layer of Cu and CoSb3. The investigation focused on thermal aging results of single CoSb3 layer at different temperatures and various aging durations of time. TGA, SEM-EDS, and GIXRD were used to investigate the thermal weight loss, elemental composition and phase characterization of CoSb3thin films, respectively; furthermore, the aging conditions of Cu/Ti/CoSb3 were determined by the results of single CoSb3 layer after aging tests. The result of TGA showed that there was a weight loss at 480 oC due to sublimation of Sb. SEM observation indicated that grain growth of the CoSb3 film occurred at 400 oC after aging for 48 hours, and voids appeared on the thin film and resulted in discontinuity of thin film. Besides, because of Sb sublimation, CoSb3 phase totally transformed to CoSb2, and partial CoSb2 became CoSb at 450 oC for 120 hours. The proper operating temperature of CoSb3 thin films should be less than 400 oC; therefore, the module of Cu/Ti/CoSb3 was aged at 300 oC for different durations of time to discuss the Cu diffusion on CoSb3 surface. The diffusivity of Cu in CoSb3 at 300 oC is about {10}^{-7}(cm^2/s). The contact resistivities of unaged and aged Cu/Ti/CoSb3 were measured. The contact resistivities of Cu/Ti/CoSb3 increased with prolonging aging durations. Consequently, another alternative adhesion layer should be chosen between Cu and CoSb3. | en_US |