Volatile Hexavalent Oxo-amidinate Complexes: Molybdenum and Tungsten Precursors for Atomic Layer Deposition

Mouat, Aidan R.; Mane, Anil U.; Elam, Jeffrey W.; Delferro, Massimiliano; Marks, Tobin J.; Stair, Peter C.

doi:10.1021/acs.chemmater.6b00248

Cited by 48 publications

(25 citation statements)

References 132 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In a recent work, WO 2 ( t BuAMD) (AMD = acetamidinato) was reported and coupled with H 2 O for growing WO 3 via ALD. 216 However, this ALD process was not well investigated.…”

Section: Layered Transition Metal Oxides Moomentioning

confidence: 99%

Atomic Layer Deposition of Two-Dimensional Layered Materials: Processes, Growth Mechanisms, and Characteristics

Cai

Han

Wang

et al. 2020

Matter

107

View full text Add to dashboard Cite

Since the discovery of graphene, there has been an ever-increasing interest in two-dimensional (2D) layered materials with exceptional properties. To this end, a variety of synthesis methods have been developed. However, it is still challenging to produce large-scale high-quality single-crystalline 2D materials. In this regard, atomic layer deposition (ALD) has recently shown great promise and has stimulated more and more research efforts, ascribed to its unique growth mechanism and distinguished capabilities to achieve nanoscale films with excellent uniformity, unrivaled conformality, and atomic-scale controllability. This review comprehensively summarizes recent progress on ALD for 2D atomic sheets, including 25 different materials and more than 80 ALD processes. This work highlights different technical routes to ALD, their precise controllability, and their underlying principles for 2D materials. It is expected that this work will help boost more research efforts for controllable growth of high-quality 2D materials via ALD.

show abstract

“…In a recent work, WO 2 ( t BuAMD) (AMD = acetamidinato) was reported and coupled with H 2 O for growing WO 3 via ALD. 216 However, this ALD process was not well investigated.…”

Section: Layered Transition Metal Oxides Moomentioning

confidence: 99%

Atomic Layer Deposition of Two-Dimensional Layered Materials: Processes, Growth Mechanisms, and Characteristics

Cai

Han

Wang

et al. 2020

Matter

107

View full text Add to dashboard Cite

show abstract

“…Due to the similar chemical properties of molybdenum and tungsten, analogous compounds have often been used as ALD precursors to deposit oxides of both metals, including [M(CO)6], [37][38][39] [40][41][42][43] and [MO2( t Buamd)2] (M = Mo, W). 44 However, some differences have been reported in the reactivity of the molybdenum and tungsten compounds under ALD conditions. For example, [W(N t Bu)2(NMe2)2] reacts with H2O, 43 whereas the corresponding Mo compound requires the use of more reactive O3 or O2 plasma.…”

Section: Introductionmentioning

confidence: 99%

Atomic Layer Deposition of Molybdenum and Tungsten Oxide Thin Films Using Heteroleptic Imido-Amidinato Precursors: Process Development, Film Characterization, and Gas Sensing Properties

et al. 2018

View full text Add to dashboard Cite

Heteroleptic bis(tert-butylimido)bis(N,N'-diisopropylacetamidinato) compounds of molybdenum and tungsten are introduced as precursors for atomic layer deposition (ALD) of tungsten and molybdenum oxide thin films using ozone as the oxygen source. Both precursors have similar thermal properties, but exhibit different growth behavior. With the molybdenum precursor, high growth rates up to 2 Å/cycle at 300 °C and extremely uniform films are obtained, although the surface reactions are not completely saturative. The corresponding tungsten precursor enables saturative film growth with a lower growth rate of 0.45 Å/cycle at 300 °C. Highly pure films of both metal oxides are deposited and their phase as well as stoichiometry can be tuned by changing the deposition conditions. The WOx films crystallize as -WO3 at 300 °C and above while the films deposited at lower temperatures are amorphous. Molybdenum oxide can be deposited as either amorphous ( 250 °C), crystalline suboxide (275 °C), a mixture of suboxide and α-MoO3 (300 °C), or pure α-MoO3 films ( 325 °C). MoOx films are further characterized by synchrotron photoemission spectroscopy and temperaturedependent resistivity measurements. A suboxide MoOx film deposited at 275 °C is demonstrated to serve as an efficient hydrogen gas sensor at a low operating temperature of 120 °C.

show abstract

“…The as-synthesized WO 3 thin films are porous and can be crystallized by a post-annealing treatment. Nevertheless, the annealing causes spontaneous formation of nanowires that are randomly oriented on the surface, decreasing the surface coverage without affecting the roughness 208. HWALD based on a tungsten wire, heated at 660 °C under successive N 2 , O 2 and H 2 atmospheres that acts as the metal precursor allows depositing tungsten oxide.…”

mentioning

confidence: 99%

Atomic layer deposition of stable 2D materials

Hao¹,

Marichy²,

Journet³

2018

2D Mater.

View full text Add to dashboard Cite

Following the graphene isolation, strong interest in two dimensional (2D) materials has been driven by their outstanding properties. Their typical intrinsic structure, including strong in-plane covalent bonding and weak out-of-plane Van der Waals interaction, makes them highly promising in diverse areas such as electronics, catalysis, and environment. Growth of 2D materials requires a synthesis approach able to control the deposition onto a support at the atomic scale. Thanks to their simplicity, versatility and ability to control thickness at the angstrom level, Atomic Layer Deposition (ALD) and its variant Atomic Layer Etching (ALET) appear as ones of the most suited techniques to synthesize 2D materials. The development of ALD technique for fabricating 2D materials in the last ten years justifies reviewing its most recent groundbreaking discoveries and progresses. Particular attention will be paid to stable 2D materials especially graphene, h-BN, Mo and W dichalcogenides and few monolayered metal oxides. Specificities and outputs of ALD for 2D material as well as emerging directions and remaining technical challenges will be highlighted. layers. This kind of materials exhibits interesting properties related to their size restriction: electronic confinement, modifying both optical and electronic properties, and high surface to volume ratio that affects the mechanical and chemical properties. 4,5 Therefore, 2D materials are highly attractive due to their potential in cutting edge domains such as micro-, and opto-electronics 4,6 as well as renewable energy, 4,7-9 catalysis, 10,11 gas sensing 12,13 and environment. 4,7,14,15 They are also exciting because of their possibility to be stacked into VdW heterostructures combining and/or tuning their chemical and physical properties. 6,[16][17][18] However, since 2D materials are atomically thin, a suitable manufacturing process capable of controlling their fabrication in terms of structure, composition, thickness, defects, purity and crystallinity without degradation of their original properties is necessary. Two approaches can be considered: the top-down and bottom-up synthetic routes. 19 Historically, top-down approach has first been developed using mechanical and chemical exfoliation techniques, 1,2,20,21 the first example being the well-known graphene exfoliation using scotch tape.Later on, etching processes have been adapted. Recently, Atomic Layer Etching (ALET), 22 the top down variant of Atomic Layer Deposition (ALD), has been introduced for fabricating 2D materials. On the other hand, bottom-up techniques have largely been developed using conventional thin film deposition. These techniques include sputtering, evaporation and Chemical Vapor Deposition (CVD). 3,23,24 However, they are mainly based on either high temperature processes, substrate restrictive deposition or low thickness control. 21,25,26 Amongst all the fabrication processes, ALD appears to be one of the most suited techniques to synthesize 2D materials, because of its simplicity, versatility and c...

show abstract

Volatile Hexavalent Oxo-amidinate Complexes: Molybdenum and Tungsten Precursors for Atomic Layer Deposition

Cited by 48 publications

References 132 publications

Atomic Layer Deposition of Two-Dimensional Layered Materials: Processes, Growth Mechanisms, and Characteristics

Atomic Layer Deposition of Two-Dimensional Layered Materials: Processes, Growth Mechanisms, and Characteristics

Atomic Layer Deposition of Molybdenum and Tungsten Oxide Thin Films Using Heteroleptic Imido-Amidinato Precursors: Process Development, Film Characterization, and Gas Sensing Properties

Atomic layer deposition of stable 2D materials

Contact Info

Product

Resources

About