Interface engineering of mixed-dimensional van der Waals heterostructures

초록

Van der Waals (vdW) heterostructures, utilizing 2-dimensional (2D) semiconducting materials such as transition metal dichalcogenides (TMDs), have attracted considerable interest for their superior physical and electrical properties over traditional silicon-based semiconductors. A critical aspect of such heterostructures is the optical transitions that can be modulated by atomic configurations at their interfaces, though the design space within 2D remains largely limited. Expanding this design space into a 3-dimensional approach by creating mixed-dimensional vdW heterostructures with precisely controlled junction geometry is pivotal for uncovering new excitonic device properties. In this work, we have engineered interfaces of mixed-dimensional vdW heterostructures comprising 1D PbI2 vdW nanowires and 2D MoSe2 TMD monolayers by manipulating the growth direction of PbI2 layer stacking. Using the vapor-liquid-solid (VLS) approach, growth directions of PbI2 nanowires were controlled in two distinct orientations, with stackings both perpendicular and parallel to their axial direction. Upon dry transferring these nanowires onto MoSe2 monolayers, we observed variations in the photoluminescence (PL) energy shift and intensity in MoSe2 based on the PbI2 nanowire's contacting layer orientation. First-principle calculations revealed the band alignment disparities at the PbI2/MoSe2 interface as influenced by the nanowire orientation, providing essential insights into the interface engineering of vdW heterostructures and facilitating the design of innovative ultrathin electronic devices.