2D Transition Metal Dichalcogenide Thin Films Obtained by Chemical Gas Phase Deposition Techniques

Abstract

Ultrathin 2D transition metal dichalcogenide (TMD) thin films have attracted much attention due to their very good electrical, optical, and electrochemical properties. Chemical vapor deposition (CVD) and atomic layer deposition (ALD), which is in some regards an enhanced version of CVD, are techniques that can provide exceptionally conformal large‐area coatings, even for complex surface geometries. Besides, these techniques include the transport of one or more precursor chemicals in the gas phase onto a substrate. Subsequently, a chemical reaction occurs, resulting in the deposition of a film of a solid material on the substrate. One of the advantageous aspects of chemical deposition methods, such as CVD and ALD, is the growth of thin films onto a variety of substrates as well as 3D structures. Because of their chemical approach, these techniques are well suited to synthesizing 2D materials (2DMs) with a low defect concentration. Furthermore, the scalability would allow industrial application, as opposed to, e.g., micromechanical cleavage. Here, the recent progress in 2D TMD thin films is reviewed and the current applications of these materials fabricated by CVD and ALD are surveyed.

Pressure‐Tunable Ambipolar Conduction and Hysteresis in Thin Palladium Diselenide Field Effect Transistors

“…Two neighboring Se atoms in the puckered morphology form a covalent Se−Se bond with ∼1.6 Å puckering distance. [14] Compared to other TMDCs, [15][16][17][18][19][20] PdSe2 has a higher stability in air and is an indirect semiconductor with bandgap from 1.3 eV for the monolayer to 100 meV or less for the bulk. [12] Such a high bandgap tunability is one of the most remarkable properties of PdSe2 that has no equals in other 2D semiconducting materials.…”

Atomic Layer Deposition-Derived Nanomaterials: Oxides, Transition Metal Dichalcogenides, and Metal–Organic Frameworks

“…For the preparation of TMD materials directly by ALD, some reports and reviews have been published, − which have made some systematic conclusions on the precursors, materials types, and characterizations. However, due to the limitation of the organic precursors of ALD, the complexity of the whole process (such as the equipment construction and exhaust gas treatment) and the high cost (normally the precursors), a facile strategy based on the first-step ALD and second-step thermal treatment has become an attractive way to fabricate controllable TMDs layers .…”

Scalable and Universal Route for the Deposition of Binary, Ternary, and Quaternary Metal Sulfide Materials from Molecular Precursors

“…Metal chalcogenides constitute an important family of medium to narrow band gap semiconductors. Much attention has been given to the synthesis of binary metal chalcogenides, such as FeS, CdS, CoS, ZnS, SnS, PbS, NiS, MnS, Ag 2 S, Cu 2 S, In 3 S 2 , Bi 2 S 3 , Ga 2 S 3 , Sb 2 S 3 , WS 2 , and MoS 2 for applications in optoelectronics, − photovoltaics, − piezoelectronics, thermoelectronics, − and, for the layered metal chalcogenides, as solid lubricants in mechanical systems. − Furthermore, many ternary and quaternary metal sulfides, for example, copper iron sulfide (CuFeS 2 , CFS) and copper zinc tin sulfide (CZTS, Cu 2 ZnSnS 4 ), are used as absorber layers in thin film photovoltaic devices because of their photoelectric characteristics, which are suitable for potentially inexpensive and sustainable solar energy generation. − Various methods have been used for the deposition of metal chalcogenide thin films, such as chemical vapor deposition, electrodeposition, anodization, successive ionic adsorption and reaction (SILAR), electroconversion, chemical bath deposition, and solution–gas interface techniques. − Among those techniques, spray deposition is potentially a very simple and cost-effective technique for the deposition of metal sulfide films for large and complex surfaces.…”