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.

We report a new piezoelectric design scheme and flexible polyurethane foams with d33 piezocoefficients up to 244 ± 30 pC N−1. Doping nonpolar polymers with polar molecules creates highly polar materials, while mesostructures yield advantageous mechanical properties for piezoelectric response.

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Wetc hemical screening reveals the very high reactivity of Mo(NMe 2 ) 4 with H 2 Sf or the low-temperature synthesis of MoS 2 .This observation motivated an investigation of Mo(NMe 2 ) 4 as av olatile precursor for the atomic layer deposition (ALD) of MoS 2 thin films.H erein we report that Mo(NMe 2 ) 4 enables MoS 2 film growth at recordl ow temperatures-as lowas608 8C. The as-deposited films are amorphous but can be readily crystallized by annealing.I mportantly,t he low ALD growth temperature is compatible with photolithographic and lift-off patterning for the straightforwardfabrication of diverse device structures.Stimulated by the landmark discovery of two-dimensional (2D) monolayer graphene [1] and the vast body of subsequent work delineating the rich physical phenomena associated with the electronic structure of graphene, [2] interest has expanded to the exploration of inorganic graphene-analogous 2D materials. [3] Central to this family of materials are 2D layered transition metal dichalcogenides,MX 2 (M = Mo,W;X= S, Se, Te ), [4] themost notable of which is MoS 2 .Whereas graphene is az ero-band-gap-energy conductor,M oS 2 is al ayered semiconductor with athickness-dependent optical band gap in the range of 1.2-1.8 eV. [5] Mono-and few-layer MoS 2 have been demonstrated to possess properties [6] suitable for awide range of electronic [7] and optoelectronic [8] applications,a nd more recently for valleytronics [9] and spintronics. [10] Additionally, 2D MoS 2 has been utilized for battery, [11] gas, [12] and biosensor applications, [13] and extensively for catalytic hydrodesulfurization [14] and hydrogen evolution processes. [15,16] It is thus not surprising that MoS 2 has in recent years become one of the most intensely studied subjects in materials chemistry and materials science. [17] To date,awide range of synthetic approaches to monoand few-layer MoS 2 have been reported;t hese include hydrothermal [18] and electrochemical synthesis, [19] thermolysis of Mo-and S-containing species, [20] sulfurization of Mo-containing seed layers, [12,21] micromechanical [7b, 22] and liquid exfoliation of bulk MoS 2 , [23] as well as physical [24] and chemical vapor deposition [25] (PVD and CVD,r espectively). [26] The most commonly employed methods,e xfoliation and CVD, have,h owever, significant limitations.T op-down methods such as exfoliation can suffer from solvent contamination and ultimately yield collections of discrete flakes rather than continuous films.Bottom-up approaches such as CVD,while promising for MoS 2 film growth on solid supports,o ften require high volatilization/reaction temperatures which limit substrate scope and patterning techniques such as photolithography. [26] Thep recise,l arge-scale growth of mono-or few-layer MoS 2 on insulating substrates would enable the scalable fabrication of atomically thin high-performance transistors,p hotodetectors,a nd other desirable products on at echnologically relevant scale;t his currently represents asignificant challenge. [4,25c] Atomic layer d...

Atomic Layer Deposition of MoS2 with controlled crystallinity on nanoporous graphene foams are highly promising hierarchical materials for numerous applications. A trade-off between the defect density and crystallinity for improved HER performance is reported.

There is a growing concern among state policy makers that unrestrained debt may exceed politically acceptable or financially sustainable levels of debt. Many states have established limits to restrict debt, but many of these limits are circumvented through issuing more complex and specialized bonds. In this article, we focus on the use of debt limits as an instrument to manage a state's debt in context of two key questions: (1) under what circumstances should a state consider multiple debt limits and (2) if multiple limits are established, what factors should be considered in setting such multiple limits. In addressing these issues, we consider the theoretical and conceptual issues associated with setting debt limits, we highlight current state debt limit policies, and discuss factors that appear to be influencing decisions to establish and set multiple limits.

The weak van der Waals bonding between monolayers in layered materials enables fabrication of heterostructures without the constraints of conventional heteroepitaxy. Although many novel heterostructures have been created by mechanical exfoliation and stacking, the direct growth of 2D chalcogenide heterostructures creates new opportunities for large-scale integration. This paper describes the epitaxial growth of layered, p-type tin sulfide (SnS) on n-type molybdenum disulfide (MoS2) by pulsed metal–organic chemical vapor deposition at 180 °C. The influence of precursor pulse and purge times on film morphology establishes growth conditions that favor layer-by-layer growth of SnS, which is critical for materials with layer-dependent electronic properties. Kelvin probe force microscopy measurements determine a built-in potential as high as 0.95 eV, and under illumination a surface photovoltage is generated, consistent with the expected Type-II band alignment for a multilayer SnS/MoS2 heterostructure. The bottom-up growth of a nonisostructural heterojunction comprising 2D semiconductors expands the combinations of materials available for scalable production of ultrathin devices with field-tunable responses.