Anisotropic assembly and reorganization of noble metals on black phosphorus van der Waals template

Black phosphorus (BP), an emerging layered semiconducting crystal, exhibits intriguing properties associated with its puckered in-plane structure. In particular, BP can serve as a template with remarkable van der Waals epitaxial effect owing to its strong anisotropic template effect. Herein, we investigated the assembly behavior of Au and Ag physically deposited on a BP template via transmission electron microscopy techniques. The results show that the orientation, assembly morphology, and crystallinity of metals can be tuned by controlling the BP substrate temperature during deposition. Electron diffraction analysis confirmed that elevated substrate temperature aids the selective formation of [110] oriented Ag and Au films by suppressing the [111] orientation. Moreover, the morphological shape and crystallinity of metals in the initial assembly mode showed temperature-dependent anisotropic effect. This study aids in understanding mechanisms of oriented metal epitaxy on anisotropic two-dimensional crystals, leading to the formation of high-quality metal-semiconductor van der Waals heterojunctions.