Utilizing Near-Field Scanning Optical Microscopy Measurements to Probe Laser Crystallization and Reamorphization in Phase Change Sb2S3 Thin Films

Phase change materials (PCMs) are seeing tremendous interest for their use in reconfigurable photonic devices. Understanding the volume of the phase change is critical to the construction of devices. In this work, we demonstrate the ability to crystallize and reamorphize Sb₂S₃ thin films using a 405 nm laser and nondestructively quantify partial volumetric crystallization with nanoscale resolution via near-field scanning optical microscopy (NSOM). We provide an analytical description of the NSOM measurements and correlate the results with a model of laser/Sb₂S₃ interactions that includes laser irradiance power, thermal transport, and phase change kinetics. The results demonstrate a relationship between computational modeling and physical device behavior, which is critical for the creation of phase change-based devices.