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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.

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Fig. 1: LDE growth of wafer-scale, globally aligned monolayer MoS2 nanoribbons.
Fig. 2: Polarization-resolved SHG measurement and DF-STEM characterization.
Fig. 3: Atomically resolved imaging and proposed mechanism for LDE growth of MoS2 nanoribbons on the ledge of β-Ga2O3 (100).
Fig. 4: Optical, electrical characterizations and batch fabrication of MoS2 nanoribbon FET.

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The data from this study are available from the corresponding authors on reasonable request.


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V.T. and J.-H.F. are indebted to the support from the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under award no. OSR-2018-CARF/CCF-3079. V.T. acknowledges support from the KAUST Catalysis Center (KCC) and physical science division. C.P.C., T.-A.C., M.-Y.L. and L.-J.L. thank the Taiwan Semiconductor Manufacturing Company (TSMC). W.-H.C. acknowledges support from the Ministry of Science and Technology of Taiwan (MOST-108-2119-M-009-011-MY3, MOST-107-2112-M-009-024-MY3) and from the CEFMS of National Chiao Tung University supported by the Ministry of Education of Taiwan. V.T. and A.A. thank C.-H. Lien and L. Cavallo for their support; H.-L. Tang; M.-H. Chiu; and C.-C. Tseng for assistance with device architecture and CVD.

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A.A., L.-J.L. and V.T. conceived the project. A.A., J.-H.F., Y.W., M.H. and R.A. performed the synthesis of the TMD nanoribbons and heterostructures, and carried out the Raman, PL and AFM characterizations. C.-C.H., T.-A.C., M.-Y.L. and J.-H.F. fabricated the FETs and conducted the associated calculations. D.R.N., E.Y. and T.D.A. performed and analysed C-AFM and hyper PL spectra. S.B. synthesized and provided the single-crystal Cu (111) for hBN. S.-H.B. and J.K. transferred the 2D TMD and heterostructures. C.P.C. and Z.C. performed the first-principles calculations. A.A., S.L. and J.-H.F. performed the DF-STEM and cross-sectional HAADF-STEM. C.-J.L., W.-T.H. and W.-H.C. executed the SHG analysis. All of the authors discussed and contributed to the results. A.A., L.J.L. and V.T. wrote the paper.

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Correspondence to Lain-Jong Li or Vincent Tung.

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Supplementary Discussions 1–3 and Figs. 1–17.

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Aljarb, A., Fu, JH., Hsu, CC. et al. Ledge-directed epitaxy of continuously self-aligned single-crystalline nanoribbons of transition metal dichalcogenides. Nat. Mater. 19, 1300–1306 (2020).

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