High‐Stability van Der Waals Structures of GeTe/Sb<sub>2</sub>Te<sub>3</sub> Superlattices for 100× Increased Durability Phase‐Change Memory (PCM) by Low‐Temperature Atomic Layer Deposition
Rong‐Jiang Zhu, Rongxuan Zhao, Ke Gao, Zhuo‐Ran Zhang, Qiang He, Hao Tong, Xiangshui Miao
Abstract
Abstract The superlattices phase‐change memory (SL‐PCM), based on GeTe/Sb 2 Te 3 superlattices (SLs), garners considerable attention within the academic community owing to its exceptional electrical properties. While the exact mechanism remains a topic of ongoing debate, researchers widely acknowledge that the presence of van der Waals (vdW) gap structures within SLs plays a pivotal role. However, the formation of vertical nanoparticles (VNPs) from the random orientation of Sb 2 Te 3 and the substantial intermixing between GeTe and Sb 2 Te 3 due to high‐temperature fabrication processes leads to pronounced elemental intermixing during electrical operations, causing a loss of SLs properties. This investigation uses atomic layer deposition techniques, specifically Sb‐atomic seed layer and periodic quintuple layers stacking, to address issues from random orientation Sb 2 Te 3 grains and anomalous VNPs. This approach yields Sb 2 Te 3 crystalline films with a high‐stability vdW gap structures. By leveraging these films, SLs with a preferred crystallographic orientation at a notable low temperature of 90 °C are successfully fabricated. The optimized SLs exhibit remarkable structural stability and mitigate alloy phase emergence during electrical operations, resulting in a 100‐fold enhancement in device durability. This work advances reliable SL‐PCM understanding and implementation, propelling this memory technology into the next generation.