The Effect of Carbon Doping on the Crystal Structure and Electrical Properties of Sb[sub.2]Te[sub.3]

• Published in: Nanomaterials (Basel, Switzerland) Switzerland), 2023-02, Vol.13 (4)
• Main Authors: Zhang, Jie, Rong, Ningning, Xu, Peng, Xiao, Yuchen, Lu, Aijiang, Song, Wenxiong, Song, Sannian, Song, Zhitang, Liang, Yongcheng, Wu, Liangcai
• Format: Article
• Language: English
• Subjects: Carbon; Crystals; Density functionals; Mechanical properties; Structure; Tellurium; Thermal properties
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano13040671

As a new generation of non-volatile memory, phase change random access memory (PCRAM) has the potential to fill the hierarchical gap between DRAM and NAND FLASH in computer storage. Sb[sub.2] Te[sub.3] , one of the candidate materials for high-speed PCRAM, has high crystallization speed and poor thermal stability. In this work, we investigated the effect of carbon doping on Sb[sub.2] Te[sub.3] . It was found that the FCC phase of C-doped Sb[sub.2] Te[sub.3] appeared at 200 °C and began to transform into the HEX phase at 25 °C, which is different from the previous reports where no FCC phase was observed in C-Sb[sub.2] Te[sub.3] . Based on the experimental observation and first-principles density functional theory calculation, it is found that the formation energy of FCC-Sb[sub.2] Te[sub.3] structure decreases gradually with the increase in C doping concentration. Moreover, doped C atoms tend to form C molecular clusters in sp[sup.2] hybridization at the grain boundary of Sb[sub.2] Te[sub.3] , which is similar to the layered structure of graphite. And after doping C atoms, the thermal stability of Sb[sub.2] Te[sub.3] is improved. We have fabricated the PCRAM device cell array of a C-Sb[sub.2] Te[sub.3] alloy, which has an operating speed of 5 ns, a high thermal stability (10-year data retention temperature 138.1 °C), a low device power consumption (0.57 pJ), a continuously adjustable resistance value, and a very low resistance drift coefficient.