Two-dimensional (2D) materials have been considered to hold promise for transistor ultrascaling, thanks to their atomically thin body immune to short-channel effects. The lower channel size limit of 2D transistors is yet to be revealed, as this size is below the spatial resolution of most lithographic techniques. In recent years, chemical approaches such as chemical vapor deposition (CVD) and metalorganic CVD (MOCVD) have been established to grow atomically precise nanostructures and heterostructures, thus allowing for synthetic construction of ultrascaled transistors. In this review, we summarize recent developments on the precise synthesis and defect engineering of electronic nanostructures/heterostructures aiming for transistor applications. We demonstrate with rich examples that ultrascaled 2D transistors are achievable by finely tuning the “growth-as-fabrication” process and could host a plethora of new device physics. Finally, by plotting the scaling trend of 2D transistors, we conclude that synthetic electronics possess superior scaling capability and could facilitate the development of post-Moore nanoelectronics.

Two-dimensional transition metal dichalcogenides (TMDs) exhibit promising application prospects in the domains of electronic devices, optoelectronic devices and spintronic devices due to their distinctive energy band structures and spin−orbit coupling properties. Cr-based chalcogenides with narrow or even zero bandgap, covering from semiconductors to metallic materials, have considerable potential for wide-band photodetection and two-dimensional magnetism. Currently, the preparation of 2D CrX_n (X = S, Se, Te) nanosheets primarily relies on chemical vapor deposition (CVD) and molecule beam epitaxy (MBE), which enable the production of high-quality large-area materials. This review article focuses on recent progress of 2D Cr-based chalcogenides, including unique crystal structure of the CrX_n system, phase-controlled synthesis, and heterojunction construction. Furthermore, a detailed introduction of room-temperature ferromagnetism and electrical/optoelectronic properties of 2D CrX_n is presented. Ultimately, this paper summarizes the challenges associated with utilizing 2D Cr-based chalcogenides in preparation strategies, optoelectronics devices, and spintronic devices while providing further insights.

As an emerging group III−VI semiconductor two-dimensional (2D) material, gallium selenide (GaSe) has attracted much attention due to its excellent optical and electrical properties. In this work, high-quality epitaxial growth of few-layer GaSe nanoflakes with different thickness is achieved via chemical vapor deposition (CVD) method. Due to the non-centrosymmetric structure, the grown GaSe nanoflakes exhibits excellent second harmonic generation (SHG). In addition, the constructed GaSe nanoflake-based photodetector exhibits stable and fast response under visible light excitation, with a rise time of 6 ms and decay time of 10 ms. These achievements clearly demonstrate the possibility of using GaSe nanoflake in the applications of nonlinear optics and (opto)-electronics.

Single-element two-dimensional (2D) tellurium (Te) which possesses an unusual quasi-one-dimensional atomic chain structure is a new member in 2D materials family. 2D Te possesses high carrier mobility, wide tunable bandgap, strong light-matter interaction, better environmental stability, and strong anisotropy, making Te exhibit tremendous application potential in next-generation electronic and optoelectronic devices. However, as an emerging 2D material, the research on fundamental property and device application of Te is still in its infancy. Hence, this review summarizes the most recent research progresses about the new star 2D Te and discusses its future development direction. Firstly, the structural features, basic physical properties, and various preparation methods of 2D Te are systemically introduced. Then, we emphatically summarize the booming development of 2D Te-based electronic and optoelectronic devices including field effect transistors, photodetectors and van der Waals heterostructure photodiodes. Finally, the future challenges, opportunities, and development directions of 2D Te-based electronic and optoelectronic devices are prospected.