SbSe/ZnSb stacked thin films with multi-level phase transition for high density phase change memory applications

As a highly integrated non-volatile memory device, phase change memory (PCM) has attracted considerable attention. In this paper, SbSe/ZnSb (SS/ZS) stacked thin films were developed for high density phase change memory applications. SS/ZS stacked thin films show two pronounced resistance steps with the increase in temperature and possess excellent thermal stability. The X-ray diffraction reveals that Sb, Sb2Se3 phases crystallize first, hexagonal ZnSb phase forms then at higher temperatures. The stacked thin films exhibit subtle variations in thickness and roughness after crystallization. Ultrafast crystallization speed (9.68 ns) in the SS(25 nm)/ZS(25 nm) thin film was validated by picosecond laser pump-probe system. Phase-change memory cells based on SS(25 nm)/ZS(25 nm) stacked thin film can realize multi-level data storage and the whole SET and RESET operations can be implemented with a 20 ns electrical pulse. Thus, SS/ZS stacked thin films have advantages for multi-level data storage capability, better thermal stability, and fast phase change speed, and are therefore good candidates for high density PCM device.