A surface chemistry route to molybdenum sulfide and germanide films using the single-source precursor tetrakis(diethylaminodithiocarbomato)molybdate(IV)

Abstract

We report for the first time the direct deposition of crystalline molybdenum sulfide (MoS 2) using a single-source precursor based on tetrakis(diethylaminodithiocarbomato)molybdate(IV) (abbreviated as Mo(Et 2NCS 2) 4). The chemistry of this precursor adsorbed on a range of substrates (silicon, germanium, gold-coated germanium, nickel, etc.) has been studied using in situ X-ray photoelectron spectroscopy. The Mo(Et 2NCS 2) 4 precursor can be evaporated at 300 °C; its vapor adsorbs on most surfaces at room temperature and decomposes by 400 °C to form crystalline MoS 2. Using this method, high-quality, basal plane-oriented MoS 2 can be grown on nickel by a one-step thermal evaporation process for the first time. Interestingly, choosing elemental substrates which form eutectic alloys with gold favors the elimination of sulfur from the MoS 2 film. This results in Mo intermetallic compound formation at the eutectic temperatures of the Au and substrate element. Unpredecented low-temperature growth of tetragonal MoSi 2 or orthorhombic MoGe 2 on Au-coated silicon or germanium, respectively, has been obtained via this eutectic phase-mediated diffusional reaction. Hollow carbon nanofibers are produced if the precursor is dosed onto Au-Si substrate at 1000 °C, mediated by the catalytic effect of Au-Mo.