Ultrafast optical manipulation of atomic motion in multilayer Ge-Sb-Te phase change materials

¹ Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8573, Japan
² Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba Central 4, 1-1-1 Higashi, Tsukuba 305-8562, Japan

Abstract

Phase change random access memory devices have evolved dramatically with the recent development of superlattice structure of Ge-Sb-Te material (GST-SL) in terms of its low power consumption. The phase change in GST-SL is mainly characterized by the displacement of Ge atoms. Here we examine a new phase change method, that is the manipulation of Ge-Te bonds using linearly-polarized femtosecond near-infrared optical pulses. As a result, we found that the p-polarized pump pulse is more effective in inducing the reversible and irreversible displacement of Ge atoms along [111] direction in the local structure. This structural change would be induced by the anisotropic carrier-phonon interaction along the [111] direction created by the p-polarized pulse.