In Situ Observation of Dynamic Crystal Growth of CuInP2S6 van der Waals Crystals

CuInP2S6 (CIPS) 2D van der Waals material has recently received significant attention due to its multifunctional properties, such as ferroelectricity, pyroelectricity, electrocaloricity, and negative piezoelectricity. The material is a promising candidate for applications in ferroelectric field-effect transistors, photodetectors, and electrocaloric cooling devices. High quality CIPS crystals are the key to these applications. Up to date, CIPS crystals have been grown using solid-state reactions and chemical vapor transport techniques while the underlying growth mechanism remains poorly understood. In this study, we employed laser-based interferometry to observe the in-situ nucleation and growth of CIPS crystals. By reconstructing the amplitude and phase of the scattered light from the crystal surfaces using a Python library, we were able to characterize the microscale nucleation and growth topography of the crystals. The growth rates were also determined. The in-situ work laid a groundwork for growth high-quality and large-scale CuInP2S6 crystals.