Low‐Temperature Atomic Layer Deposition of MoS₂ Films

Abstract

Wet chemical screening reveals the very high reactivity of Mo(NMe ) with H S for the low-temperature synthesis of MoS . This observation motivated an investigation of Mo(NMe ) as a volatile precursor for the atomic layer deposition (ALD) of MoS thin films. Herein we report that Mo(NMe ) enables MoS film growth at record low temperatures-as low as 60 °C. The as-deposited films are amorphous but can be readily crystallized by annealing. Importantly, the low ALD growth temperature is compatible with photolithographic and lift-off patterning for the straightforward fabrication of diverse device structures.

Nucleation mechanism during WS2 plasma enhanced atomic layer deposition on amorphous Al2O3 and sapphire substrates

“…This avoids the need for a material transfer from a growth substrate to the target substrate. Nonetheless, only few ALD processes of MoS2 and WS2 are reported, using dihydrogen sulfide (H2S) in combination with either metalhalide precursors such as molybdenum pentachloride (MoCl5) or tungsten hexafluoride (WF6), or metal-organic precursors such as molybdenum hexacarbonyl (Mo(CO)6), tris(2,2,6,6-tetramethylheptane-3,5-dionato) molybdenum(III) (Mothd3) or tetrakis(dimethylamido) molybdenum Mo(NMe2)4 [13][14][15][16][17] . In the absence of a template for epitaxial seeding, the layers are either amorphous or polycrystalline, depending on the deposition temperature (typically below 450C) and precursor chemistry.…”

“…The majority of the reports discusses the ALD process conditions and the physical properties of the grown layers [13][14][15][16][17] . In general, the crystal domain size is smaller for ALD than for CVD (< 100 nm).…”

Large area few-layer TMD film growths and their applications

“…Low temperature growths, while suffering in crystallinity, are essential for realizing these possibilities. Pursuing this, Jurca et al [61] used an organic Mo precursor to synthesize monolayer MoS 2 on the millimeter scale on Si/SiO 2 at 60 • C. Taking advantage of this incredibly low growth temperature, Jurca et al lithographically pre-patterned the growth substrate to shape the resultant growth [61] While crystallinity was poor, post-annealing improved structural quality [61]. ALD TMD growths are relatively novel compared to more traditional CVD growth strategies, so there is still much to be done in terms of optimization.…”

Initial stage of atomic layer deposition of 2D-MoS2 on a SiO2 surface: a DFT study

“…Atomic layer deposition (ALD) is a deposition technique that consists of cyclic surface reactions of subsequent exposure of a precursor and a co-reagent to the surface. Owing to its self-limiting chemistry, ALD offers unique possibilities for high-quality, low temperature growth [13][14] (<450 °C) of conformal thin-films with Å level thickness control. A first successful demonstration of a low temperature process flow for integration of back-gated 2D transistors in the BEOL (Back End Of Line), which included ALD of 2D-WS 2 , has been reported recently 15 .…”

“…Most studies concentrate on MoCl 5 and Mo(CO) 6 precursor [16][17] with H 2 S or CH 3 SSCH 3 as the co-reagent. Lately also a study appeared in which Mo(NMe 2 ) 4 was used as the ALD precursor 14 .…”