Hongxin Yang, Luping Shi, Rong Zhao, Hock Koon Lee, Jianming Li, Kian Guan Lim, Lung Tat Ng, and Tow Chong Chong Growth-Dominant Superlattice-Like Medium and Its Application in Phase Change Memory ECS J. Solid State Sci. Technol. 2015 4(3): N13-N17; doi:10.1149/2.0091503jss
Ideal growth-dominant (GD) phase change material is needed for lateral Phase change memory (PCM). We propose the concept of GD superlattice-like (SLL) phase change structure. GeTe and Sb7Te3 were selected to form the GD SLL structure. Through detailed thin film studies, it was found that the crystallization temperature and resistivity of GeTe and Sb7Te3 were thickness dependent. The crystallization behavior of GeTe/Sb7Te3 SLL phase change structure shows a single-threshold and growth-dominant, indicating that it is an ideal candidate for lateral PCM. It was found that the crystallization and melting temperatures of GeTe/Sb7Te3 SLL phase change structure could be tuned by thickness ratio. The crystallization temperature of GeTe/Sb7Te3 SLL phase change structure increase with increasing thickness ratio of GeTe/Sb7Te3. GeTe/Sb7Te3 SLL structure built with a thickness ratio of 1.6:1 (GeTe to Sb7Te3) exhibited the lowest melting temperature compared to other thickness ratio. For a typical lateral PCM employing such GeTe/Sb7Te3 SLL phase change structure, stable SET/RESET operations with a low RESET current of 1.5mA, high programming speed of 30 nanoseconds, a good endurance above 105 cycles and a high RESET/SET resistance ratio window of 20 were achieved, demonstrating strong potentials in next generation non-volatile memory application.