Investigation of the optical properties on Ge2Sb2Te5/Si superlattice-like thin films

We employ the spectroscopic ellipsometry technique to study the optical properties in Ge2Sb2Te5/Si superlattice-like thin films because of the potential use in optical storage. In the reflectivity measurements on the amorphous state, it is found that the reflection spectra could be substantially modified by changing the film thickness, the polarized direction of the light and the incident angle θ, respectively. It is believed that more Ge atoms in ultrathin films are tetrahedrally coordinated instead of the defective octahedral-like sites and brings about the evolution of the optical reflectivity. The isotropic resonant bonding environment in the crystallization state is also observed by the reflection spectra. © 2018, National Institute of Optoelectronics. All rights reserved.