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Abstract For several decades after Moore's Law is proposed, there is a continuous effort to reduce the feature‐size of transistors. However, as the size of transistors continues to decrease, numerous challenges and obstacles including severe short channel effects (SCEs) are emerging. Recently, low‐dimensional materials have provided new opportunities for constructing small feature‐size transistors due to their superior electrical properties compared to silicon. Here, state‐of‐the‐art low‐dimensional materials‐based transistors with small feature‐sizes are reviewed. Different from other works that mainly focus on material characteristics of a specific device structure, the discussed topics are utilizing device structure design including vertical structure and nano‐gate structure, and nanofabrication techniques to achieve small feature‐sizes of transistors. A comprehensive summary of these small feature‐size transistors is presented by illustrating their operation mechanism, relevant fabrication processes, and corresponding performance parameters. Besides, the role of small feature‐size transistors based on low‐dimensional materials in further reducing the small footprint is also clarified and their cutting‐edge applications are highlighted. Finally, a comparison and analysis between state‐of‐art transistors is made, as well as a glimpse into the future research trajectory of low dimensional materials‐based small feature‐size transistors is briefly outlined.

Since the discovery of innovative two-dimensional (2D) materials, significant efforts have been dedicated to exploring their intriguing properties and emerging applications. Among all candidates, transition metal dichalcogenides (TMDs) have proven to be exceptional for gas sensing, while defects engineering has been introduced to modify the pristine TMDs for better gas sensing performances. In this review, we systematically summarize types of defects, advanced characterization techniques, and state-of-the-art controllable synthetic methods. Various types of defects in TMDs can induce diverse changes in chemical and electron structures, which are closely correlated with gas sensing ability. Therefore, connections between defects and gas sensing mechanisms and performances have been addressed based on both defect categories and electron affinity of gases. This review will be a guide for researchers in defective materials and open up the field of precisely synthesis chemistry and deepen the understanding of the underlying effects of defects in other 2D materials.