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

Abstract

Tetrakis(dithiocarboxylato)molybdenum(IV) complexes of the type Mo(S2CR)4 (R = Me, Et, iPr, Ph) were synthesized, characterized and prescreened as precursors for aerosol assisted chemical vapor deposition (AACVD) of MoS2 thin films....

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

“…A few single-source precursors for the chemical vapor deposition of MoS 2 have been reported, including Mo(S t Bu) 4 , 38 Mo-(S 2 CNR 2 ) 4 (R = Et, n Bu), 39 [MoCl 4 ( n Bu 2 S) 2 ], 40 and Mo-(S 2 CMe) 4 . 41 In conventional CVD, where precursors are directly evaporated or sublimed in bubblers, volatility of the compounds is critical, providing a limitation on the precursors that can be studied. However, the need for volatile precursors can be circumvented using aerosol-assisted CVD (AACVD), in which the precursor is dissolved in a suitable solvent and the solution is nebulized.…”

“…46 The film grown at 500 °C from cis-Mo(CO) 4 (TMTU) 2 (Figure 4b) featured vertically oriented nanostructures resembling those that have been observed in thin film samples of MoS 2 grown by AACVD from in THF (300−475 °C), 65 or Mo(S 2 CMe) 4 in toluene (500 °C). 41 The film grown at 400 °C from cis-Mo(CO) 4 (TMTU) 2 (Figure 4c) appeared mostly smooth except for widely spaced bubble-like structures that were distributed throughout the surface. AFM was conducted on the film deposited using 2 at 400 °C, which showed an RMS roughness (Sq) value of 1.740 nm.…”

“…Thin films of MoS 2 can be prepared by a variety of methods such as physical exfoliation, , chemical exfoliation, physical vapor deposition, and chemical vapor deposition (CVD). − CVD of MoS 2 generally involves the use of coreactant systems with a molybdenum source, such as MoO 3 or Mo­(CO) 6 , and a sulfur source, which is most commonly elemental sulfur. ,− Other sulfur sources used in the deposition of MoS 2 include the toxic and hazardous compounds H 2 S, , CS 2 , and Et 2 S. , Thin films can also be deposited from single-source precursors that contain all of the atoms of the desired film in a single compound. A few single-source precursors for the chemical vapor deposition of MoS 2 have been reported, including Mo­(S t Bu) 4 , Mo­(S 2 CNR 2 ) 4 (R = Et, n Bu), [MoCl 4 ( n Bu 2 S) 2 ], and Mo­(S 2 CMe) 4 …”

“…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 . ,,− …”

Molybdenum(III) Amidinate: Synthesis, Characterization, and Vapor Phase Growth of Mo-Based Materials

“…Critically, what both techniques require is access to suitable molecular precursors. − Even though this need has motivated the search for and discovery of a number of Mo precursors for ALD and/or CVD, ,,− a number of which are now commercially available, − there is still a vast disparity between the amount of Mo-based materials work being done and the availability of diverse molecular starting materials. Thus, there is a continuing need to discover new molecular building blocks which can enable different vapor phase growth processes over broad temperature ranges and with a variety of co-reactants.…”