Flux-Assisted Growth of Degenerate n-Type SnSe ₂ Layers

Tin diselenide (SnSe 2 ) 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 SnSe 2, 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 SnSe 2 flakes with significantly enlarged domain sizes exceeding 300 μm. The synthesized SnSe 2 exhibits a well-ordered 1T-phase lattice structure, a high Hall mobility of 262.5 cm 2 ·V –1 ·s –1, and an electron concentration of 8.23 × 10 13 cm –2, confirming its degenerate n-type nature. Furthermore, the SnSe 2 -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 SnSe 2 for p–n + van der Waals tunneling heterostructures and in-sensor reservoir computing.