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Abstract The large‐scale growth of semiconducting thin films on insulating substrates enables batch fabrication of atomically thin electronic and optoelectronic devices and circuits without film transfer. Here an efficient method to achieve rapid growth of large‐area monolayer MoSe₂films based on spin coating of Mo precursor and assisted by NaCl is reported. Uniform monolayer MoSe₂films up to a few inches in size are obtained within a short growth time of 5 min. The as‐grown monolayer MoSe₂films are of high quality with large grain size (up to 120 µm). Arrays of field‐effect transistors are fabricated from the MoSe₂films through a photolithographic process; the devices exhibit high carrier mobility of ≈27.6 cm²V^–1s^–1and on/off ratios of ≈10⁵. The findings provide insight into the batch production of uniform thin transition metal dichalcogenide films and promote their large‐scale applications. 

Gas flows are often analyzed with the theoretical descriptions formulated over a century ago and constantly challenged by the emerging architectures of narrow channels, slits, and apertures. Here, we report atomic-scale defects in two-dimensional (2D) materials as apertures for gas flows at the ultimate quasi-0D atomic limit. We establish that pristine monolayer tungsten disulfide (WS 2 ) membranes act as atomically thin barriers to gas transport. Atomic vacancies from missing tungsten (W) sites are made in freestanding (WS 2 ) monolayers by focused ion beam irradiation and characterized using aberration-corrected transmission electron microscopy. WS 2 monolayers with atomic apertures are mechanically sturdy and showed fast helium flow. We propose a simple yet robust method for confirming the formation of atomic apertures over large areas using gas flows, an essential step for pursuing their prospective applications in various domains including molecular separation, single quantum emitters, sensing and monitoring of gases at ultralow concentrations.