Toward Wafer‐Scale Production of 2D Transition Metal Chalcogenides

Abstract

When the timeline reached 2004, graphene, the single layer of graphite, was discovered through a scotch-tape exfoliation method and was found to have ultrahigh mobility. [25][26][27] Various 2D materials such as transition metal chalcogenides (TMCs), [28][29][30] boron nitrides (BNs), [31,32] black phosphorus, [33,34] and some new materials including Si, [35] Te, [36] and black arsenic-phosphorus [37] were subsequently synthesized, enabling the fabrication of numerous novel devices. The field of 2D materials is now making strong voice, which is no longer ignored by the scientific and technological community. [38][39][40] Among the various 2D materials, the TMCs constituted by the transition metal elements (M) and the chalcogen elements (X) are a large family. M can range from group 4B to group 10 in the periodic table, while X is S, Se, or Te. [41][42][43][44][45][46][47] Figure 1a exhibits the binary TMCs that have already been explored. This variation of composition of elements transfers to a wide range of properties ranging from insulators (e.g., HfS 2 ), [48,49] semiconductors (e.g., MoS 2 , WS 2 ), [50,51] semimetals (e.g., MoTe 2 , TiSe 2 ), [52,53] to metals (e.g., NbSe 2 , VS 2 ). [54][55][56] Furthermore, TMCs can form alloys in the formula such as WSe 2−x S x , with composition-tunable properties. [57][58][59] Unlike semimetallic graphene, semiconducting TMCs usually possess a bandgap. For example, MoS 2 exhibits a bandgap, transitioning from indirect bandgap to direct bandgap when it thins from bulk phase to monolayer (Figure 1b), boosting the photoluminescence (PL) efficiency. [51,[60][61][62] Additionally, inversion symmetry breaking and large spin-orbit interaction, resulting in two energetic degenerate but inequivalent valleys in the band structure of a TMC (Figure 1c), may lead to breakthroughs in valleytronics and spintronics. [63][64][65][66][67][68][69][70] A few TMCs (e.g., NbSe 2 , TaS 2 , VSe 2 ) have shown superconductivity, [71,72] charge density wave [73,74] and Mott transition (transition from metal to nonmetal). [75,76] In addition, some novel TMCs such as Fe 3 GeTe 2 display intrinsic magnetism with gate-tunable Curie points. [66,77] Semimetallic TMCs like WTe 2 show topological structures in the energy band, enabling the study on topological physics. [78,79] The rich intrinsic properties and superior tunability of TMCs hold great promise for all kinds of technologically important applications in electronics, optoelectronics, spintronics, valleytronics, etc. (Figure 1d). [51,[80][81][82][83][84][85][86][87][88][89][90][91] Due to numerous unique properties of 2D TMCs, devices such as transistors, photodetectors (PDs), and photodiodes based on 2D TMCs have been actively pursued. The ultimate destination of the miniaturization of the electronic devices will 2D transition metal chalcogenides (TMCs) have attracted tremendous interest from both the scientific and technological communities due to their variety of properties and superior tunability through layer number, composition, and inter...

Wafer-scale MoS2 with water-vapor assisted showerhead MOCVD

“…Being a member of the transition metal dichalcogenides (TMD) [1], MoS 2 unique electronic [2,3] and optical properties [4] combined with high mechanical flexibility [5,6] make it an attractive candidate for a potential new generation of wearable devices [7], flexible sensors [8][9][10] or nanoelectronics [2,11] as well as heterostructure research and development [12][13][14][15][16][17][18][19][20]. Therefore, after years of extensive study, the shift of academic focus from small, lab-scale synthesis methods towards the prototype applications and scalable processes is inevitable [21][22][23].…”

“…12–20 Therefore, after years of extensive study, the shift of academic focus from small, lab-scale synthesis methods towards prototype applications and scalable processes is inevitable. 21–23…”

“…[12][13][14][15][16][17][18][19][20] Therefore, aer years of extensive study, the shi of academic focus from small, lab-scale synthesis methods towards prototype applications and scalable processes is inevitable. [21][22][23] One of the most vigorously investigated aspects of scaling up the research and application of MoS 2 is large-scale, uniform and high quality material synthesis. [24][25][26][27][28][29][30][31][32] Over the years, numerous efforts to understand, optimize and grow large-area 2D lms have been reported.…”

CrS2-Modulated Enhanced Catalytic Properties of CdS/MoS2 Heterostructures Toward Photodegradation and Electrochemical OER Kinetics

“…Metal chalcogenide nanostructures have piqued researchers’ attention in a variety of fields, including electrochemistry, physics, and material sciences . Binary chalcogenides, specially, MoS 2 , CdS, and CrS 2 , are trending for photocatalysis, electrocatalysts, biosensors, memory, capacitors, and other electronic devices due to their tunable band gap, durability, low cost, thermal stability, and outstanding electrical and optical properties.…”

Single Nanoflake Photoelectrochemistry Reveals Intrananoflake Doping Heterogeneity That Explains Ensemble-Level Photoelectrochemical Behavior

“…Advances in mechanical exfoliation have also led to the production of high-quality macroscopic monolayers and artificial heterostructures, , which opens the exciting possibility of creating macroscopic p–n junctions with controllable properties defined by the parent bulk material. Hence, the 2D materials community is advancing large-scale production methods for potentially low-cost and high-performance thin film photoelectrodes. − …”