Nonlinear Optical Response and Ultrafast Carrier Dynamics in Single-Crystalline Sb Nanosheets with van der Waals Epitaxy

Antimony (Sb) is a novel elementary material that has recently garnered extensive attention owing to its intriguing physical properties, such as topological, thermoelectric, and photoelectric properties. Further studies regarding Sb crystal structures will enable a better understanding of their properties and facilitate their application. In this study, Sb nanosheets in the form of triangular islands with tunable thicknesses are grown on the mica substrate through chemical vapor deposition. Characterization is performed via scanning electron microscopy, transition electron microscopy, and atomic force microscopy; it is shown that the largest crystallite size exceeds 30 μm. Nonlinear transmission measurements reveal that Sb nanosheets under excitation with a 1030 nm laser possess the maximum nonsaturation two-photon absorption (TPA) coefficient of 8.49 × 10³ cm/GW, which indicated that Sb possesses great nonlinear optical properties and may be applied in advanced photonic and optoelectronic devices.