Multicycle High‐Temperature Electric Properties of Al 2 O 3 /YZA/TGO Multilayer Thin Films

Understanding the high‐temperature electrical behavior of oxide multilayer films is essential for the design of robust microdevices operating in extreme environments. However, their conduction mechanisms under repeated thermal cycling are not yet fully understood. In this study, the high‐temperature conduction mechanism of Al 2 O 3 /YZA/TGO multilayer thin films was explored under repeated thermal cycles (from the 1 st to the 6 th cycle) up to 1000°C. Results reveal that the conduction mechanism evolves significantly with both temperature and the number of cycles. During the initial cycle, grain boundaries and film interfaces present high energy barriers, and the dominant conduction mechanisms are Ohmic conduction at low electric fields and space‐charge‐limited conduction and trap‐filled limited (TFL) conduction at higher fields. As the number of thermal cycles increases, grain growth and metal diffusion from the substrate reduce the internal conduction barriers. In later cycles, conduction remains Ohmic at low fields, while the TFL mechanism increasingly dominates at high fields. A significant drop in film resistivity is observed starting from the 2 nd cycle, which is attributed to the formation of conductive channels caused by interfacial diffusion of metal elements and the generation of oxygen vacancies. These results provide insights into the temperature‐ and cycle‐dependent electrical conduction behavior of oxide multilayers and lay a foundation for their future applications in high‐temperature microelectronic systems.