Investigation of Phase Segregation in Ge ₁₅ Sb ₈₅ Phase Change Material

Atomic migration is a key challenge in phase change (PC) materials. Although several techniques have been proposed to address phase segregation, the role of phase segregation in PC materials remains unclear. In this study, the local structural changes during phase segregation in the Ge15Sb85 PC material are investigated using Raman and X‐ray photoelectron spectroscopy (XPS). We then propose two feasible solutions to address the phase segregation. First, in‐situ depth profiling of the etched crystalline films probed by XPS reveals an enhancement in GeSb bonds and a decline in GeGe bonds, indicating the suppression of undesired phase segregation in the scaled‐down crystalline films. Second, the 3‐bit multilevel accumulative switching technique, realized using low‐energy (12 mJ/cm 2 ) nanosecond laser pulses in a 100 nm Ge15Sb85 thin film, reduces the GeGe Raman vibration modes responsible for phase segregation. Additionally, the simulations predict a maximum growth velocity of 35 m/s with an optimized, scaled‐down thickness of 19 nm. Hence, the results demonstrate that phase‐segregation suppression can be achieved in scaled‐down crystalline Ge15Sb85 films, and, together with accumulative switching, phase‐segregation can be tackled to a greater extent, thereby improving the write endurance of highly‐scalable binary PC material for future photonic memory applications.