Flux-Assisted Growth of Degenerate n-Type SnSe₂ Layers

Tin diselenide (SnSe₂) is a two-dimensional (2D) semiconductor with a high electron affinity (∼5.2 eV) and inherent n⁺-type conductivity. While conventional chemical vapor deposition (CVD) has been investigated for the growth of SnSe₂, the domain sizes are typically limited to ∼50 μm. This limitation arises primarily from difficulties in precise control of the thermodynamics of nucleation and growth along with the kinetics of vapor-phase transport. To address this issue, we employed flux-assisted growth (FAG) to facilitate liquid-phase precursor transport via a molten flux. As a result, we achieved crystalline SnSe₂ flakes with significantly enlarged domain sizes exceeding 300 μm. The synthesized SnSe₂ exhibits a well-ordered 1T-phase lattice structure, a high Hall mobility of 262.5 cm²·V^-1·s^-1, and an electron concentration of 8.23 × 10¹³ cm^-2, confirming its degenerate n-type nature. Furthermore, the SnSe₂-based devices show reproducible photoresponse cycles governed by trap-mediated processes yielding a multitime scale fading memory. Our findings provide insights into the feasibility of flux-grown SnSe₂ for p-n⁺ van der Waals tunneling heterostructures and in-sensor reservoir computing.