Recent advances in low-dimensional materials have revealed that one-dimensional (1D) monatomic chains serve as ideal platforms for exploring exotic quantum phases and emergent phenomena arising from spatial confinement. The synthesis of such structures within well-defined and stable templates represents a key step toward harnessing their unique physical properties. In this study, we utilize the naturally formed, spatially confined channels between self-assembled silicon nanoribbons (SiNRs) on a Si(111) surface as an ideal template for growing highly ordered potassium (K) monatomic chains. Using scanning tunneling microscopy and density functional theory (DFT) calculations, we systematically characterize the confined potassium (K) atoms by high aspect ratio SiNRs and the resulting electronic properties. Our results show that the unique confined space created by the SiNRs reduces the adsorption energy of K atoms by 0.09 eV. This reduction leads to preferential adsorption of K atoms between strands of double- and multistranded SiNRs, where they form a distinct triangular morphology with three neighboring Si atoms. This triangular structure is a result of charge transfer, as confirmed by our DFT calculations. At higher coverage, the K atoms self-assemble into 1D zigzag chain structures along the SiNRs. Notably, the adsorption of K atoms is reversible and can be precisely controlled by a scanning tunneling microscopy tip voltage pulse without causing damage to the SiNRs. Furthermore, the adsorption of K dynamically shifts the position of the Dirac cone relative to the Fermi level, offering an effective means of electronic tuning. This work not only elucidates the formation of artificial 1D K chains within the confined space of SiNRs, but also opens up avenues for the synthesis of atomically precise nanostructures through the use of special confined spaces.

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• Doping effects
• Nanoribbon
• Silicene
• Scanning tunneling microscopy
• Scanning tunneling spectroscopy