R&D: Sn, In, or Al Doped ZnSb Thin Film Candidates for Phase Change Material

The feasibility of Sn, In, or Al doped ZnSb thin film as candidates
for phase change material

By Yimin Chen, Xiang Shen1, Guoxiang, Tiefeng Xu, Rongping Wang, Shixun Dai, and Qiuhua Nie

This work was financially supported by the Natural Science Foundation of China, the Public Project of Zhejiang Province, the Young Leaders of academic climbing project of the Education Department of Zhejiang Province, the Natural Science Foundation of Zhejiang Province, the Scientific Research Foundation of Graduate School of Ningbo University, and sponsored by K. C. Wong Magna Fund in Ningbo University.

Abstract:
The potentials of Sn, In, or Al doped ZnSb thin film as candidates for phase change materials have been studied in this paper. It was found that the Zn-Sb bonds were broken by the addition of the dopants and homopolar Zn-Zn bonds and other heteropolar bonds, such as Sn-Sb, In-Sb, and Al-Sb, were subsequently formed. The existence of homopolar Sn-Sn and In-In bonds in Zn 50Sb36Sn14 and Zn 41Sb36In23 films, but no any Al-Al bonds in Zn 35Sb30Al35 film, was confirmed. All these three amorphous films crystallize with the appearance of crystalline rhombohedral Sb phase, and Zn 35Sb30Al35 film even exhibits a second crystallization process where the crystalline AlSb phase is separated out. The Zn 35Sb30Al35 film exhibits a reversible phase change behavior with a larger Ea (around 4.7eV), higher Tc (aronnd 245°C), better 10-yr data retention (around 182°C), less incubation time (20ns at 70mW), and faster complete crystallization speed (45ns at 70mW). Moreover, Zn 35Sb30Al35 film shows the smaller root-mean-square (1.654nm) and less change of the thickness between amorphous and crystalline state (7.5%), which are in favor of improving the reliability of phase change memory.