In this work, we present direct evidence of phase separation in Sb 2 Te films considered for integration into phase change memory (PCM) cells. X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive spectrometer (EDS) experiments indicate that significant phase separation occurs in the Sb 2 Te films during annealing at 300 °C, leading to the formation of Sb and Sb 2 Te 3 phases. By integrating insights from Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), we analyze the atomic vibrational states and bonding characteristics of the films. The results indicate that the mechanism underlying phase separation in Sb 2 Te films is primarily attributed to the rupture of van der Waals bonds between layers, accompanied by the formation of more stable covalent bonds at high temperatures. The findings from this work offer valuable guidance for developing PCM devices that are structurally stable.
Zheng et al. (2026) studied this question.