Investigation of crystallization behavior and structure of nanocomposite multilayer phase change thin films with zinc antimony and germanium antimony

Abstract

Multilayer Zn50Sb50/Ge8Sb92 (ZS/GS) thin films were proposed and fabricated by alternate sputtering. The crystallization behaviors of nanocomposite ZS/GS thin films induced by heating were investigated by in situ resistance measurement. The crystallization behaviors of ZS/GS thin films can be regulated by tuning the thickness ratio and periods. The multilayer [ZS (8 nm)/GS (4 nm)]4 ([ZS(8)/GS(4)]4) thin film exhibits a high crystallization temperature (~ 245 °C), a large crystallization activation energy (2.61 eV), and high data retention ability (168 °C). The phase structure and thickness variation of the [ZS(8)/GS(4)]4 thin film were analyzed through x-ray diffraction (XRD) and x-ray reflection (XRR), respectively. The volume shrinkage during crystallization was as small as 3.9%. The multilayer structure and interface stability were confirmed by using transmission electron microscopy (TEM). A picosecond laser pump-probe system was used to evaluate the transition speed. The crystallization and amorphization periods of the [ZS(8)/GS(4)]4 thin film were only about 6.2 ns and 3.9 ns, respectively.