Organic steep-slope nano-FETs: A rational design based on two-dimensional covalent-organic frameworks

We report a strategy to design organic steep-slope nanoscale field-effect transistors (nano-FETs) with subthreshold swing (SS) breaking the thermionic limit of 60 mV/dec at room temperature. The devices are based on a family of two-dimensional (2D) covalent-organic frameworks (COFs) with a square lattice and building blocks of metallophthalocyanine (MPc). Our first-principles calculations reveal that lattice mismatch-free metal/semiconductor monolayer heterojunctions, which serve as both electrodes and channel of the devices, can be obtained by modulating monolayer 2D MPc-COFs with suitable MPc. The cold-source mechanism and the interplay between electrodes and channel are of critical importance for realizing doping-free organic steep-slope nano-FETs, of which the SS can reach as small as 37.2 mV/dec at 300 K. Our findings offer a route to overcome the “Boltzmann tyranny” in low-power nanoelectronic devices by rational design of organic 2D materials, which are much more diverse and flexible in material design than their inorganic counterparts. • Organic nano-FETs with subthreshold swing breaking the thermionic limit of 60 mV/dec at room temperature were proposed. • The devices are based on two-dimensional covalent-organic frameworks of metallophthalocyanine. • The cold-source mechanism and the interplay between electrodes and channel are the underlying mechanism for the devices.