Thermal Transport in Chalcogenide-Based Phase Change Materials: A Journey from Fundamental Physics to Device Engineering

Advancements in nanofabrication processes have propelled nonvolatile phase change materials (PCMs) beyond storage-class applications. They are now making headway in fields such as photonic integrated circuits (PIC), free-space optics, and plasmonics. This shift is owed to their distinct electrical, optical, and thermal properties between their different atomic structures, which can be reversibly switched through thermal stimuli. However, the reliability of PCM-based optical components is not yet on par with that of storage-class devices. This is in part due to the challenges in maintaining a uniform temperature distribution across the PCM volume during phase transformation, which is essential to mitigate stress and element segregation as the device size exceeds a few micrometers. Understanding thermal transport in PCM-based devices is thus crucial as it dictates not only the durability but also the performance and power consumption of these devices. This article reviews recent advances in the development of PCM-based photonic devices from a thermal transport perspective and explores potential avenues to enhance device reliability. The aim is to provide insights into how PCM-based technologies can evolve beyond storage-class applications, maintain their functionality, and achieve longer lifetimes.