Shanghai Key Laboratory for R&D and Application of Metallic Functional Materials, School of Materials Science and Engineering, Tongji University, Shanghai 201804, People's Republic of China. School of Mathematics and Physics, Jiangsu University of Technology, Changzhou 213001, People's Republic of China.
Nanotechnology. 2017 Oct 6;28(40):405206. doi: 10.1088/1361-6528/aa82d1.
Superlattice-like GeTe/GeSb (SLL GT/GS) thin film was systematically investigated for multi-level storage and ultra-fast switching phase-change memory application. In situ resistance measurement indicates that SLL GT/GS thin film exhibits two distinct resistance steps with elevated temperature. The thermal stability of the amorphous state and intermediate state were evaluated with the Kissinger and Arrhenius plots. The phase-structure evolution revealed that the amorphous SLL GT/GS thin film crystallized into rhombohedral Sb phase first, then the rhombohedral GeTe phase. The microstructure, layered structure, and interface stability of SLL GT/GS thin film was confirmed by using transmission electron microscopy. The transition speed of crystallization and amorphization was measured by the picosecond laser pump-probe system. The volume variation during the crystallization was obtained from x-ray reflectivity. Phase-change memory (PCM) cells based on SLL GT/GS thin film were fabricated to verify the multi-level switching under an electrical pulse as short as 30 ns. These results illustrate that the SLL GT/GS thin film has great potentiality in high-density and high-speed PCM applications.
超晶格状 GeTe/GeSb（SLL GT/GS）薄膜被系统地研究用于多层存储和超快速切换相变存储应用。原位电阻测量表明，SLL GT/GS 薄膜在升温时表现出两个明显的电阻阶跃。利用 Kissinger 和 Arrhenius 图评估非晶态和中间态的热稳定性。相结构演化表明，非晶 SLL GT/GS 薄膜首先结晶成三方相 Sb 相，然后结晶成三方相 GeTe 相。利用透射电子显微镜证实了 SLL GT/GS 薄膜的微观结构、层状结构和界面稳定性。通过皮秒激光泵浦探测系统测量了结晶和非晶化的相变速度。利用 X 射线反射率获得了结晶过程中的体积变化。基于 SLL GT/GS 薄膜制备了相变存储（PCM）单元，以验证在 30ns 短电脉冲下的多级切换。这些结果表明，SLL GT/GS 薄膜在高密度和高速 PCM 应用中具有巨大的潜力。
