Transition metal dichalcogenides (TMDCs) materials has a great potential for applications in electronics and optoelectronics devices owing to its tuning band gap strongly depending on the thickness. Among the TMDCs materials, monolayer MoS₂, as a direct band gap semiconductor, has fascinating optical, electrical, magnetic, thermal and mechanical properties. 2D MoS₂ is expected to be widely used in photodetectors, photovoltic devices, field effect transistors, memory devices, valley electronics, spintronics, thermoelectrics, micro-nanoelectromechanical devices and systems. At present, chemical vapor deposition (CVD) is the most promising method to synthesize large-area two-dimensional transition metal chalcogenide (such as MoS₂, MoSe₂, WS₂ and WSe₂) atomic layers. Electronic and optoelectronic devices of CVD-made 2D MoS₂ have been extensively investigated. In this review, we summarize extensive chemical vapor deposition methods such as thermal decomposition of (NH₄)₂MoS₄, sulfurization of metal Mo or MoO_3-x thin film, gas-phase synthesis of sulfur-based precursors and direct sulfurization of molybdenum foils. Then, the preparation of different 2D heterostructures has also been introduced. On the basis of preparing the 2D materials, we introduce in detail the research progress of MoS₂-based transistors, photoelectric devices, flexible devices and related heterostructures. Finally, we analyze the research of two-dimensional materials with further applications in semiconductor devices.

Contents
1 Introduction
2 Basic character of 2D molybdenum disulfide
2.1 Crystal structure and band structure
2.2 Optical properties
3 Synthesis of 2D molybdenum disulfide via chemical vapor deposition
3.1 Thermal decomposition of (NH₄)₂MoS₄
3.2 Sulfurization of metal Mo or MoO_3-x thin films
3.3 Gas-phase synthesis of sulfur-based precursors
3.4 Direct sulfurization of molybdenum foils
3.5 Synthesis of 2D layered heterostructures
4 Application of 2D molybdenum disulfide in electric devices
4.1 Field effect transistors based on 2D MoS₂
4.2 Photodetectors based on 2D MoS₂
4.3 Flexible electronic devices
4.4 2D layered heterostructures devices
5 Conclusion