Phase Tailoring of In2Se3 Toward van der Waals Vertical Heterostructures via Selenization of γ‐InSe Semiconductor

Abstract The polymorphic nature of In 2 Se 3 leads to excellent phase‐dependent physical properties including ferroelectricity, photoelectricity, and especially the intriguing phase change ability, making the precise phase modulation of In 2 Se 3 of fundamental importance but very challenging. Here, the growth of In 2 Se 3 with desired‐phase is realized by temperature‐controlled selenization of van der Waals (vdW) layered bulk γ‐InSe. Detailed results of Raman spectroscopy, scanning electron microscopy (SEM), and state‐of‐the‐art spherical aberration‐corrected transmission electron microscopy (Cs‐TEM) clearly and consistently show that β‐In 2 Se 3 , 3R α‐In 2 Se 3 , and 2H α‐In 2 Se 3 can be perfectly obtained at ≈270, ≈300, and ≈600 °C, respectively. Further comprehensive atomic imaging analyses confirm that the seeding material, InSe, plays a critical role in the low‐temperature epitaxial growth of vdW‐layered In 2 Se 3 , and, more interestingly, β‐In 2 Se 3 acts as an intermediate phase between 3R and 2H α‐In 2 Se 3 transitions. This investigation not only provides a simple yet versatile strategy for the phase modulation of In 2 Se 3 , but also sheds light on the temperature‐dependent phase evolution of In 2 Se 3 .