Laser‐Induced Crystallization and Amorphization of Ge‐Rich GST Thin Films Monitored In Situ with Synchrotron X‐Ray Diffraction

This study explores laser‐induced crystallization and amorphization processes in thin films of Ge‐rich GST (GGST), a tailored phase change material (PCM), monitored in situ using synchrotron X‐ray diffraction. GGST's high crystallization temperature makes it a promising material for embedded memory applications. Experiments employed an 800 nm femtosecond laser source, varying fluence and pulse parameters to induce phase transitions. Key findings include fluence‐dependent thresholds for crystallizing Ge and GST, along with precise control over reversible amorphization. Crystallization maps highlight the differences in fluence and pulse requirements for the transformations. Repeated cycling between amorphous and crystalline states, mimicking PCM operations, confirms the feasibility of controlled phase transitions. Surface imaging using scanning electron microscopy revealed fluence‐induced changes, including ripple formation and ablation at higher intensities. The potential of ultrafast laser irradiation to precisely manipulate GGST phase changes is demonstrated, establishing a foundation for future research on time‐resolved experiments on this and other PCMs.