Changes of optical, dielectric, and structural properties of Si15Sb85 phase change memory thin films under different initializing laser power

The optical, dielectric, and structural characteristics of Si15Sb85 phase change memory thin films under a moving continuous-wave laser initialization are studied by using spectroscopic ellipsometry and high-resolution transmission electron microscopy. The dependence of complex refractive index, dielectric functions, absorption coefficient, and optical band gap of the films on its crystallization extents formed by the different initialization laser power are analyzed in detail. The structural change from as-deposited amorphous phase to distorted rhombohedra-Sb-like crystalline structure with the increase of initialization laser power is clearly observed with sub-nanometer resolution. The optical and dielectric constants, the relationship between them, and the local atomic arrangements of this new phase change material can help explain the phase change mechanism and design the practical phase change memory devices.

Research highlights
► We study the optical, dielectric, and structural characteristics of Si15Sb85 phase change memory thin films under a moving continuous-wave laser initialization.
► The optical and dielectric constants, absorption coefficient of Si15Sb85 change regularly with the increasing laser power.
► The optical band gaps of Si15Sb85 irradiated upon different power lasers were calculated.
► HRTEM images of the samples were observed and the changes of optical and dielectric constants are determined by crystalline structures changes of the films.