Atomically Precise Bottom-Up Fabrication of Ultra-Narrow Semiconducting Zigzag BiP Nanoribbons

1D semiconductors with atomically precise edge and well-controlled width hold significant promise as channel materials for next-generation electronics. Here a method to fabricate the narrowest zigzag-edged bismuth phosphide (BiP) nanoribbons (NRs) is presented, achieving widths of three atoms (≈0.7 nm), through molecular beam epitaxy on bismuthene in a wide P coverage range. Using scanning tunneling microscopy and first-principles calculations, it is revealed that these BiP NRs exhibit a blue-phosphorene-like structure, with a theoretical bandgap of 0.38 eV. Notably, first-principles calculations reveal spin-polarized states located on the zigzag edges, presenting an option for spintronics applications. Formation of these uniform BiP NRs is attributed to tensile strain from lattice-registry confinement. During epitaxial growth, P clusters act dually as feedstock and catalysts, suggesting a self-catalyzed growth mechanism. The bottom-up strategy offers an effective approach for the atomically precise fabrication of 1D BiP NRs, paving the way for the creation of diverse low-dimensional binary materials with tailored chemical and electronic properties, facilitated by selecting suitable elemental 2D materials as substrates.