Unravelling and circumventing failure mechanisms in chalcogenide optical phase change materials

TL;DR

This paper investigates the failure mechanisms of Ge2Sb2Se4Te (GSST) optical phase change materials and proposes design improvements that significantly enhance device endurance for photonic applications.

Contribution

It systematically elucidates cycling failure mechanisms in GSST and develops design rules that increase endurance to over 67,000 cycles.

Findings

Identified key failure mechanisms in GSST during electrothermal switching

Proposed design rules to mitigate failure and improve endurance

Achieved over 67,000 switching cycles in GSST devices

Abstract

Chalcogenide optical phase change materials (PCMs) have garnered significant interest for their growing applications in programmable photonics, optical analog computing, active metasurfaces, and beyond. Limited endurance or cycling lifetime is however increasingly becoming a bottleneck toward their practical deployment for these applications. To address this issue, we performed a systematic study elucidating the cycling failure mechanisms of Ge$_2$Sb$_2$Se$_4$Te (GSST), a common optical PCM tailored for infrared photonic applications, in an electrothermal switching configuration commensurate with their applications in on-chip photonic devices. We further propose a set of design rules building on insights into the failure mechanisms, and successfully implemented them to boost the endurance of the GSST device to over 67,000 cycles.