Top-Down Integration of Molybdenum Disulfide Transistors with Wafer-Scale Uniformity and Layer Controllability

Abstract

The lack of stable and efficient techniques to synthesize high-quality large-area thin films is one of the major bottlenecks for the real-world application of the 2D transition metal dichalcogenides. In this work, the growth of molybdenum disulfide (MoS₂ ) on sapphire substrates by sulfurizing the MoO₃ film deposited by atomic layer deposition (ALD) is reported. The advantages of the ALD method can be well inherited, and the synthesized MoS₂ films exhibit excellent layer controllability, wafer-scale uniformity, and homogeneity. MoS₂ films with desired thickness can be obtained by varying MoO₃ ALD cycles. The atomic force microscope and Raman measurements demonstrate that the ALD-based MoS₂ has good uniformity. Clear Raman shift as a function of the film thickness is observed. Field-effect transistor devices are fabricated through a transfer-free and top-down process. High On/Off current ratio (≈10⁴ ) and medium-level electron mobilities (≈0.76 cm² V^-1 s^-1 for monolayer, and 5.9 cm² V^-1 s^-1 for four-layer) are obtained. The work opens up an attractive approach to realize the application of wafer-scale 2D materials in integrated circuits and systems.

Keywords: MoO3; MoS2; atomic layer deposition; sulfuration; transistors.