5TH International Congress on Technology - Engineering & Science - Kuala Lumpur - Malaysia (2018-02-01)

Interfacial Damage In Phase Change Materials Tuned Optical Structures

We study the diffusion of metal atoms into phase change chalcogenides. Phase change chalcogenides exhibit stable amorphous and crystalline states at room temperature with a substantial difference in their optical and electrical properties between states. These important materials are used in rewritable optical data storage and are now being applied to non-volatile random-access memory devices. Recently, phase change materials have been investigated for active photonics applications. They have been applied in tuneable polarisation-independent perfect absorbers at visible and mid-infrared wavelengths, optical imaging devices, nano-displays, active nano-photonics, and reconfigurable optical circuits. However, many recent publications do not consider reactions and diffusion at the interface between the metal and chalcogenide layers, which may occur. The diffusion influences the properties of the phase change layer, such as the crystallisation kinetics and optical constants. Here, we study the interface between the phase change material, Ge2Sb2Te5, and different metal layers using X-ray reflectivity (XRR) and reflectometry of metal/phase change chalcogenide stacks. We find that a diffusion barrier layer, such as Si3N4, can help to prevent the interfacial diffusion of the metal and Ge2Sb2Te5 layers.
Li Tian Chew, Weiling Dong, Li Lu, Robert Simpson