Advances in Phase Change Materials for Flexible Embedded Electronics

Nowadays smart systems, mainly for biomedical, automotive and aerospace fields, are strongly driving the request for innovative technologies to ensure in loco fast and safe data processing along with power and cost efficiency. Nevertheless, the stability, the mechanical flexibility, the huge computational and storage requirements of these applications are beyond the capability of current embedded devices. Phase-change materials (PCMs) are known as a solution to overcome the Von Neumann architecture, as active materials in a computational memory device that can in loco store data and carry out calculations at once, with a unique prospect of high performance and power efficiency. In line with the circular economy model, PCM-based devices can be fabricated with low cost technologies directly on flexible and large-area recyclable substrates. However, currently the potential of PCM materials in flexible devices is far from being fully exploited and their behavior on flexible substrates is still not clear.<br/>Recently, our research group identified a suitable PCM alloy, with excellent thermal stability and mechanical toughness. The proposed work was intended to lay the groundwork for the development of low-cost and large-area compatible processes for high performance flexible PCM-based memories. Primarily, we evaluated the compatibility of these alloys with large-area scalability and their processability on flexible substrates. The electronic properties and the compliance of the performance to the target requirements were assessed with specific figures of merit, such as the resistance contrast between the amorphous and crystalline phases and the mechanical stability through bending tests. Additionally, the structural changes induced by annealing the alloys were examined to gain insights into the onset of crystallization and to highlight some differences during crystallization between film deposited on flexible substrates and standard SiOx, used as a reference for a rigid substrate. The integration of PCMs alloys as active material in flexible memories is discussed and the prospects of PCMs for flexible edge electronics will be presented. Overall, the research work done demonstrated that the PCM features and performances are well in line with the current industrial targets for flexible edge electronics.