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

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.

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

“…Table S1 (Supporting Information) compares the elec tron mobility and On/Off current ratio between our ALD based MoS 2 device and previously reported MoS 2 FETs. The mobility of our 4L MoS 2 are comparable or even higher than those of previously reported CVD samples on SiO 2 /Si with a SiO 2 gate oxide or on sapphire substrate, [14,22,23,33,36,37] and is highest among all the published ALD based MoS 2 device research. [5,6] …”

“…All the fabricated monolayer MoS 2 FETs exhibited well defined n type transport behavior, similar to previously published work. [5,23,33] Figure 3b shows the transfer characteristics and the output characteristics were demon strated in Figure 3d. The field effect electron mobility was extracted from the liner regime of the transfer curve using the equation…”

Controlled synthesis of high-quality crystals of monolayer MoS2 for nanoelectronic device application

“…While mechanical exfoliated monolayer MoS 2 flakes display excellent electronic and optoelectronic properties, the small size and the low production of these monolayer MoS 2 flakes hinder them from further development. Synthesis of large-area MoS 2 films have been reported in the past few years [22][23][24][25][26][27]. However, the preparation of large-size monolayer MoS 2 single crystals remain to be improved in view of its superior electronic and optoelectronic characteristics [28][29][30][31].…”

Processable 2D materials beyond graphene: MoS2liquid crystals and fibres

“…7 However, integration of 2D TMDs into macrostructures while preserving their inherent properties requires processable materials that can be directly fabricated using scalable material processing and fabrication approaches without the aid of any processing additives. [8][9][10] While significant progress has been made on the production of various 2D TMDs including MoS 2 by chemical vapor deposition (CVD) growth, 11 chemical exfoliation, 12 electrochemical exfoliation, 13 and exfoliation in solvents, 14 the development of a processable 2D TMD dispersion, which is suitable for large-scale manufacturing and processing, has yet to be addressed. Such a development has indeed occurred for graphene oxide (GO) with the formation of liquid crystalline (LC) dispersions of GO [15][16][17] that have allowed the fabrication of graphene-based devices using wet-spinning, 8,9,[18][19][20] Both rigid and flexible anisotropic molecules undergo a transition from the isotropic phase to the so-called nematic phase as a function of aspect ratio and concentration.…”