High-throughput characterization of local structural imperfections in freestanding oxide membranes by lock-in...

Freestanding oxide membranes hold great promise for both intriguing low-dimensional functionalities and innovative device applications. However, randomly distributed cracks and wrinkles can severely degrade local properties and device performance. Here, we develop a lock-in thermography (LIT)-based approach for efficient and semi-quantitative detection of local structural imperfections in freestanding oxide membranes. By driving a periodic square-wave current through conductive oxide membranes (for example, SrRuO₃ and La_2/3Sr_1/3MnO₃), LIT visualizes distinct thermal fingerprints of wrinkles and cracks down to the sub-micrometer scale. Joint analyses of the LIT amplitude and phase signals yield detailed information on these structural imperfections, including their type, size, height modulation, and orientation. By introducing ultrathin conductive capping layers, we further explore the possibility of extending LIT to insulating oxide membranes. Our results establish LIT as a high-throughput approach for wide-area mapping of structural imperfections in freestanding oxide membranes, facilitating the development of reliable, uniform, and flexible oxide electronic device arrays.