Interlayer-Confined Alloying Dissolution–Precipitation Growth and Electronic Transport Modulation of Large-Area Coastline-like Fractal Bismuthene Films with Statistic Self-Similarity

The preparation of large-area, high-quality, two-dimensional metallene films often necessitates the use of high-vacuum equipment due to the high surface tension of metals. Herein, we report the growth of large-area coastline-like fractal bismuthene films with intrinsic statistical self-similarity through an interlayer-confined alloying dissolution–precipitation epitaxy method via the construction of a sandwich structure of h-BN/Cu/Mo foil with a nanoconfined space and a sequential dissolution–precipitation process. The resulting bismuthene film manifests a coastline-like fractal feature with a tunable fractal dimension and thickness regulated by the thickness of Cu film. The fractal bismuthene film can be seamlessly transferred to other substrates without incurring oxidation, impurity residues, or structural damage. A 50-nm-thick bismuthene film exhibits semimetallic properties, while an 8-nm-thick bismuthene film behaves as a p-type semiconductor, confirming a typical metal-to-semiconductor transition behavior. This study suggests the significant potential of interlayer-confined precipitation epitaxy strategy in producing large-area two-dimensional metallene films, thereby advancing the development of cutting-edge nanodevices.