Chemical Vapor Deposition of Uniform and Large-Domain Molybdenum Disulfide Crystals on Glass/Al2O3 Substrates

Abstract

Two-dimensional molybdenum disulfide (MoS₂) has attracted significant attention for next-generation electronics, flexible devices, and optical applications. Chemical vapor deposition is the most promising route for the production of large-scale, high-quality MoS₂ films. Recently, the chemical vapor deposition of MoS₂ films on soda-lime glass has attracted great attention due to its low cost, fast growth, and large domain size. Typically, a piece of Mo foil or graphite needs to be used as a buffer layer between the glass substrates and the CVD system to prevent the glass substrates from being fragmented. In this study, a novel method was developed for synthesizing MoS₂ on glass substrates. Inert Al₂O₃ was used as the buffer layer and high-quality, uniform, triangular monolayer MoS₂ crystals with domain sizes larger than 400 μm were obtained. To demonstrate the advantages of glass/Al₂O₃ substrates, a direct comparison of CVD MoS₂ on glass/Mo and glass/Al₂O₃ substrates was performed. When Mo foil was used as the buffer layer, serried small bilayer islands and bright core centers could be observed on the MoS₂ domains at the center and edges of glass substrates. As a control, uniform MoS₂ crystals were obtained when Al₂O₃ was used as the buffer layer, both at the center and the edge of glass substrates. Raman and PL spectra were further characterized to show the merit of glass/Al₂O₃ substrates. In addition, the thickness of MoS₂ domains was confirmed by an atomic force microscope and the uniformity of MoS₂ domains was verified by Raman mapping. This work provides a novel method for CVD MoS₂ growth on soda-lime glass and is helpful in realizing commercial applications of MoS₂.

Keywords: MoS2; chemical vapor deposition; glass; substrate.

Figure 1

Schematic illustration of the CVD growth system setup.

Figure 2

(a) Optical photograph of the glass/Mo substrates after the growth of MoS₂. (b) Optical photograph of the glass/Al₂O₃ substrates after the growth of MoS₂. The red rectangle corresponds to the center region, and the blue rectangle corresponds to the edge region.

Figure 3

(a,b) Optical microscope images of the MoS₂ domains synthesized on the center region of glass/Mo substrates. (c,d) Optical microscope images of the MoS₂ domains synthesized on the center region of glass/Al₂O₃ substrates. Scale bar represents 200 μm for (a,c), and 10 μm for (b,d).

Figure 4

(a,b) Optical microscope images of the MoS₂ domains synthesized on the edge region of glass/Mo substrates. (c,d) Optical microscope images of the MoS₂ domains synthesized on the edge region of glass/Al₂O₃ substrates. Scale bar represents 50 μm for (a–d).

Figure 5

(a,b) Schematic illustration of the CVD growth process on glass/Mo substrates. (c,d) Schematic illustration of the CVD growth process on glass/Al₂O₃ substrates. The blue balls and yellow balls in (b,d) represent Mo and S atoms, respectively.

Figure 6

(a,b) Raman and PL spectral of the CVD-grown MoS₂ on the center region of glass/Mo substrates. (c,d) Raman and PL spectral of the CVD-grown MoS₂ on the center region of glass/Al₂O₃ substrates.

Figure 7

(a,b) AFM image and height profile of the CVD-grown MoS₂ on glass/Al₂O₃ substrates. (c,d) Raman mapping of the CVD-grown MoS₂ on glass/Al₂O₃ substrates. Scale bar are 5 μm for (a), and Scale bars are 3 μm for (c,d).