Epitaxial growth of single-crystal violet phosphorus flakes on silicon substrates.

Violet phosphorus structure, a promising van der Waals semiconductor, has attracted growing attention due to its unique properties. It is still a big challenge to grow violet phosphorus or phosphorene on a certain substrate. Herein, violet phosphorus flakes with tuneable sizes have been directly grown on a silicon substrate using exfoliated violet phosphorene nanosheets as seeds. A chemical transport method based on P/I/Sn sources was adopted for the epitaxial growth of violet phosphorus flakes. The edges of violet phosphorene nanosheets were found to decompose initially with increasing temperature, subsequently acting as homogeneous nuclei for the growth of violet phosphorus flakes in both the lateral and vertical (out-of-plane) directions. The size of violet phosphorus flakes was found to increase with increasing reaction time. The average lateral sizes of the as-grown violet phosphorus flakes were found to increase from ∼0.98 μm to ∼41.54 μm, with average thickness increasing from ∼0.15 μm to ∼3.82 μm after 48 h of reaction. The as-grown flakes were further confirmed using a marked silicon substrate, where the violet phosphorene nanosheet seeds were found to grow from a lateral size of 0.95/1.04 μm with a thickness of 0.09/0.11 μm to 30.22/36.64 μm with a thickness of 2.31/2.57 μm after 10 h of reaction. The successful growth of violet phosphorus flakes on a silicon substrate enables the development of advanced electronic and optoelectronic devices based on violet phosphorus and phosphorene structures, enhancing the functionality of next-generation technologies.