Multiscale simulations of growth-dominated Sb$_2$Te phase-change material for non-volatile photonic applications

TL;DR

This study uses multiscale simulations to explore the crystallization behavior and optical property changes of doped Sb$_2$Te phase-change materials, informing their use in non-volatile photonic devices.

Contribution

It provides new insights into the crystallization process and optical properties of Sb$_2$Te$, highlighting differences from other phase-change materials and guiding photonic application design.

Findings

Crystallization induces wavelength-dependent dielectric changes.

Tellurium ordering affects device output in photonic applications.

Simulations reveal differences in color display and memory performance.

Abstract

Chalcogenide phase-change materials (PCMs) are widely applied in electronic and photonic applications, such as non-volatile memory and neuro-inspired computing. Doped Sb$_2$Te alloys are now gaining increasing attention for on-chip photonic applications, due to their growth-driven crystallization features. However, it remains unknown whether Sb$_2$Te also forms a metastable crystalline phase upon nanoseconds crystallization in devices, similar to the case of nucleation-driven Ge-Sb-Te alloys. Here, we carry out ab initio simulations to understand the changes in optical properties of amorphous Sb$_2$Te upon crystallization and post annealing. During the continuous transformation process, changes in the dielectric function are highly wavelength-dependent from the visible-light range towards the telecommunication band. Our finite-difference time-domain simulations based on the ab initio input reveal key differences in device output for color display and photonic memory applications upon tellurium ordering. Our work serves as an example of how multiscale simulations of materials can guide practical photonic phase-change applications.