Layer-controlled CVD growth of large-area two-dimensional MoS₂films

TLDR

In spite of the recent heightened interest in molybdenum disulfide (MoS₂) as a two‑dimensional material with substantial bandgaps and reasonably high carrier mobility, a method for the layer‑controlled and large‑scale synthesis of high‑quality MoS₂ films has not previously been established. Here, we demonstrate that layer‑controlled and large‑area CVD MoS₂ films can be achieved by treating the surfaces of their bottom SiO₂ substrates with an oxygen plasma process. The authors use oxygen plasma treatment of SiO₂ substrates followed by CVD, and confirm uniform mono‑, bi‑, and trilayer coverage across centimeter‑scale areas via Raman, UV‑Vis, and PL mapping. TEM confirms single‑crystalline monolayer and layer‑controlled bi‑ and trilayer films, and back‑gated transistors exhibit on/off ratios of ~10⁶ and mobilities of 3.6, 8.2, and 15.6 cm² V⁻¹ s⁻¹, indicating that the method enables high‑quality, scalable MoS₂ films for diverse applications.

Abstract

In spite of the recent heightened interest in molybdenum disulfide (MoS2) as a two-dimensional material with substantial bandgaps and reasonably high carrier mobility, a method for the layer-controlled and large-scale synthesis of high quality MoS2 films has not previously been established. Here, we demonstrate that layer-controlled and large-area CVD MoS2 films can be achieved by treating the surfaces of their bottom SiO2 substrates with the oxygen plasma process. Raman mapping, UV-Vis, and PL mapping are performed to show that mono, bi, and trilayer MoS2 films grown on the plasma treated substrates fully cover the centimeter scale substrates with a uniform thickness. Our TEM images also present the single crystalline nature of the monolayer MoS2 film and the formation of the layer-controlled bi- and tri-layer MoS2 films. Back-gated transistors fabricated on these MoS2 films are found to exhibit the high current on/off ratio of ∼10(6) and high mobility values of 3.6 cm(2) V(-1) s(-1) (monolayer), 8.2 cm(2) V(-1) s(-1) (bilayer), and 15.6 cm(2) V(-1) s(-1) (trilayer). Our results are expected to have a significant impact on further studies of the MoS2 growth mechanism as well as on the scaled layer-controlled production of high quality MoS2 films for a wide range of applications.