Wang Xue-Peng, Li Xian-Bin, Chen Nian-Ke, Chen Bin, Rao Feng, Zhang Shengbai
State Key Laboratory of Integrated Optoelectronics College of Electronic Science and Engineering Jilin University Changchun 130012 China.
College of Materials Science and Engineering Shenzhen University Shenzhen 518060 China.
Adv Sci (Weinh). 2021 May 14;8(13):2004185. doi: 10.1002/advs.202004185. eCollection 2021 Jul.
One central task of developing nonvolatile phase change memory (PCM) is to improve its scalability for high-density data integration. In this work, by first-principles molecular dynamics, to date the thinnest PCM material possible (0.8 nm), namely, a monolayer SbTe, is proposed. Importantly, its SET (crystallization) process is a fast one-step transition from amorphous to hexagonal phase without the usual intermediate cubic phase. An increased spatial localization of electrons due to geometrical confinement is found to be beneficial for keeping the data nonvolatile in the amorphous phase at the 2D limit. The substrate and superstrate can be utilized to control the phase change behavior: e.g., with passivated SiO (001) surfaces or hexagonal Boron Nitride, the monolayer SbTe can reach SET recrystallization in 0.54 ns or even as fast as 0.12 ns, but with unpassivated SiO (001), this would not be possible. Besides, working with small volume PCM materials is also a natural way to lower power consumption. Therefore, the proposed PCM working process at the 2D limit will be an important potential strategy of scaling the current PCM materials for ultrahigh-density data storage.
开发非易失性相变存储器（PCM）的一项核心任务是提高其用于高密度数据集成的可扩展性。在这项工作中，通过第一性原理分子动力学，提出了迄今为止可能最薄的PCM材料（0.8纳米），即单层SbTe。重要的是，其SET（结晶）过程是从非晶相到六方相的快速一步转变，没有通常的中间立方相。发现由于几何限制导致的电子空间局域化增加有利于在二维极限下使非晶相中的数据保持非易失性。衬底和覆盖层可用于控制相变行为：例如，对于钝化的SiO（001）表面或六方氮化硼，单层SbTe可在0.54纳秒甚至快至0.12纳秒内实现SET再结晶，但对于未钝化的SiO（001），则无法实现。此外，使用小体积的PCM材料也是降低功耗的自然方式。因此，所提出的二维极限下的PCM工作过程将是扩展当前PCM材料以用于超高密度数据存储的重要潜在策略。
