Mist chemical vapor deposition of crystalline MoS₂ atomic layer films using sequential mist supply mode and its application in field-effect transistors

Abstract

Molybdenum disulfide (MoS2) mono/bilayer have been systematically investigated using atmospheric-pressure mist chemical vapor deposition (mist CVD) from (NH4)2MoS4 dissolved in N-methyl-2-pyrrolidone as a precursor. Film deposition was performed by alternating MoS2 mist storage within a closed chamber and mist exhaust, i.e. sequential mist supply mode at different furnace temperatures, storage times of precursor, and repetition cycles of mist supply on thermally grown SiO2 (th-SiO2) and mist-CVD grown Al1−x Ti x O y (ATO) layers coated on p+-Si substrates. The average size of the MoS2 flake and their number of stack layers could be controlled by tuning the deposition parameters combined with substrate pretreatment. Field-effect transistors with MoS2 atomic mono/bilayer as a channel layer exhibited mobility up to 31–40 (43–55) cm2 V−1 s−1 with a threshold voltage of −1.6 (−0.5) V, subthreshold slope of 0.8 (0.11) V dec.−1, and on/off ratio of 3.2 × 104 (3.6 × 105) on th-SiO2 (ATO) layers as gate dielectric layers without mechanical exfoliation. These findings imply that mist CVD is available for the synthesis of metal transition metal dichalcogenide and metal oxide layers as channel and gate dielectric layers, respectively.

Molybdenum(iv) dithiocarboxylates as single-source precursors for AACVD of MoS2 thin films

“…64 AACVD has been also been used to deposit Fe-doped MoS 2 /Mo 2 S 3 from [CpMo (SMe) 2 ] 2 ; 60 and the related technique mist CVD has been used to deposit MoS 2 from (NH 4 ) 2 MoS 4 . 65 We now report synthesis of a series of Mo(IV) dithiocarboxylate complexes of the type Mo(S 2 CR) 4 as potential single source precursors and we demonstrate AACVD of MoS 2 from the methyl derivative Mo (S 2 CMe) 4 (Fig. 1).…”

Aerosol-Assisted Chemical Vapor Deposition of MoS2 with a Thiourea Sulfur Source: Single-Source Precursors vs Coreactant Mixtures

“…As the droplets approach the heated substrate, solvent is evaporated and removed by the carrier gas, leaving behind precursor which can decompose on the substrate to yield the desired film . This method has been used successfully in the past to deposit thin films of MoS 2 . ,,− …”

Carrier Transport Properties in Few-Layer WS0.3Se1.7/(WOx)WS0.3Se1.7 Lateral p+–n Junctions Using a Metal–Oxide–Semiconductor Field-Effect Transistor (MOSFET) Structure

“…Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) of the MX 2 family (where M = Mo or W and X = Se, S, or Te) exhibit considerable potential for next-generation device technologies owing to their novel electronic and optoelectronic properties. − Unlike the indirect bandgap in bulk TMDCs materials, a direct bandgap ( E g ) is exhibited in the monolayer form, originating a high photoluminescence quantum yield and radiative efficiency. − Additionally, the chalcogenides exhibit bandgaps ranging from the visible to near-infrared regions of the spectrum (1.1–2.0 eV), making them suitable candidates for photoelectronic applications; by contrast, most materials exhibit energy bandgaps close to an optimum value of 1.34 eV . Moreover, MX 2 materials, which possess layered structures and high refractive indices (∼4.69–5.86), display significantly higher absorption coefficients (∼5 × 10 5 cm –1 ) in the spectral range of 400–900 nm compared to Si, Ge, GaAs, perovskites, and organic absorber materials. − The presence of unsaturated d-orbitals in TMDC materials with three different polytypes in the form of 1T, 2H, and 3R and controlled filling of such d-orbitals facilitate the engineering of different properties such as band structure, charge density waves, metallic, half-metallic, superconducting, and magnetic behavior .…”