Van der waals epitaxial growth of single-crystal molecular film

ABSTRACT Epitaxy is the cornerstone of semiconductor technology, enabling the fabrication of single-crystal film. Recent advancements in van der Waals (vdW) epitaxy have opened new avenues for producing wafer-scale single-crystal 2D atomic crystals. However, when it comes to molecular crystals, the overall weak vdW force means that it is a significant challenge for small molecules to form a well-ordered structure during epitaxy. Here we demonstrate that the vdW epitaxy of Sb2O3 molecular crystal, where the whole growth process is governed by vdW interactions, can be precisely controlled. The nucleation is deterministically modulated by epilayer–substrate interactions and unidirectional nuclei are realized through designing the lattice and symmetry matching between epilayer and substrate. Moreover, the growth and coalescence of nuclei as well as the layer-by-layer growth mode are kinetically realized via tackling the Schwoebel-Ehrlich barrier. Such precise control of vdW epitaxy enables the growth of single-crystal Sb2O3 molecular film with desirable thickness. Using the ultrathin highly oriented Sb2O3 film as a gate dielectric, we fabricated MoS2-based field-effect transistors that exhibit superior device performance. The results substantiate the viability of precisely managing molecule alignment in vdW epitaxy, paving the way for large-scale synthesis of single-crystal 2D molecular crystals.