Ledge-directed epitaxy of continuously self-aligned single-crystalline nanoribbons of transition metal dichalcogenides

Two-dimensional transition metal dichalcogenide nanoribbons are touted as the future extreme device downscaling for advanced logic and memory devices but remain a formidable synthetic challenge. Here, we demonstrate a ledge-directed epitaxy (LDE) of dense arrays of continuous, self-aligned, monolayer and single-crystalline MoS₂ nanoribbons on β-gallium (iii) oxide (β-Ga₂O₃) (100) substrates. LDE MoS₂ nanoribbons have spatial uniformity over a long range and transport characteristics on par with those seen in exfoliated benchmarks. Prototype MoS₂-nanoribbon-based field-effect transistors exhibit high on/off ratios of 10⁸ and an averaged room temperature electron mobility of 65 cm² V⁻¹ s⁻¹. The MoS₂ nanoribbons can be readily transferred to arbitrary substrates while the underlying β-Ga₂O₃ can be reused after mechanical exfoliation. We further demonstrate LDE as a versatile epitaxy platform for the growth of p-type WSe₂ nanoribbons and lateral heterostructures made of p-WSe₂ and n-MoS₂ nanoribbons for futuristic electronics applications.