Two-dimensional semiconductor integrated circuits operating at gigahertz frequencies

Two-dimensional transition metal dichalcogenides could potentially be used to create transistors that are scaled beyond the capabilities of silicon devices. However, despite progress on the single-transistor level, the development of high-frequency integrated circuits remains a challenge and the operating frequency of integrated circuits based on transition metal dichalcogenides has so far been limited to the megahertz regime; this is well below the silicon complementary metal–oxide–semiconductor technology, as well as emerging technologies such as carbon nanotubes. Here we report two-dimensional semiconductor integrated circuits—five-stage ring oscillators—that operate in the gigahertz regime (up to 2.65 GHz) and are developed using a design-technology co-optimization process. The circuits are based on monolayer molybdenum disulfide field-effect transistors that have an air-gap structure, which leads to doping-free ohmic contacts and low parasitic capacitance. Technology computer-aided design simulations also suggest that our air-gap structure can potentially be scaled to the 1 nm technology node and could reach the targets set out in the IEEE International Roadmap for Devices and Systems for 2031.