R&D: Ultrafast SET/RESET Operation for Optoelectronic Hybrid Phase-Change Memory Device Cells

Applied Physics Letters has published an article written by Ben Wu, Tao Wei, Suzhou Key Laboratory for Nanophotonic and Nanoelectronic Materials and Its Devices, School of Materials Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, Jiangsu Province, China, Qianchen Liu, Suzhou Key Laboratory for Nanophotonic and Nanoelectronic Materials and Its Devices, School of Materials Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, Jiangsu Province, China, Yan Cheng, Yonghui Zheng, Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China, Ruirui Wang, Qianqian Liu, Miao Cheng, Wanfei Li, Jing Hu, Yun Ling, and Bo Liu, Suzhou Key Laboratory for Nanophotonic and Nanoelectronic Materials and Its Devices, School of Materials Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, Jiangsu Province, China.

Abstract: “Combination of nonvolatile storage and in-memory computing promises to break through the ‘memory bottleneck’ that computing device adopts von Neumann architecture with individual computing and memory unit. Thus, the advanced nonvolatile memory device with ultrafast operation speed is urgently required. Here, the optoelectronic hybrid phase-change memory based on the Ge₂Sb₂Te₅ material is proposed, where the picosecond laser induced reversible phase-change is utilized to write and erase the information while the resistance difference is adopted to realize the accurate information readout. Due to the significant difference in resistance between crystalline and amorphous states, a partial crystallization strategy can be adopted to achieve ultrafast SET operation. Results indicate that SET operation speed of the Ge₂Sb₂Te₅ film and device unit can be as fast as 52 and 130 ps, respectively, while the RESET speed reaches 13 ps. In parallel, the resistance ratio of RESET to SET state is still as high as two orders of magnitude. By using partial crystallization strategy, the phase-change induced by picosecond laser only occurs from amorphous to face-centered-cubic crystalline state with low crystallinity and the defective octahedral motif is observed in the Ge₂Sb₂Te₅ film, which is beneficial to achieve the ultrafast operation speed. At the same time, the ordered clusters existed in the as-deposited and picosecond laser induced RESET films can accelerate the nucleation process of the Ge₂Sb₂Te₅ film, which is one of the important reasons for achieving ultrafast SET speed. The optoelectronic hybrid phase-change memory with ultrafast operation speed may be one of the promising solutions for the in-memory computing.“