Realizing sub-6-nm-channel high-performance spin field-effect transistors in lateral Sc2CHO/Sc2CHF/Sc2CHO heterojunctions

In this work, nanoscale spin field-effect transistors (spin-FETs) based on lateral heterojunctions composed of two-dimensional (2D) ferromagnetic half-metallic Sc2CHO electrodes and nonmagnetic semiconductor Sc2CHF channel are theoretically designed. The channel lengths (Lc) for investigated nanoscale spin-FETs are shorter than 6 nm. The spin transport properties of these nanoscale spin-FETs are subsequently studied by using the nonequilibrium Green's function method in combination with density functional theory. Due to the strong electronic coupling at the interfaces between electrodes and channel, p-type Ohmic contacts are obtained for spin down. Calculations reveal that at very-low temperature, the spin injection efficiency can reach 100%, and the magnetoresistance ratio (MR) is generally larger than 109% for these nanoscale spin-FETs. Very-low subthreshold swing (SS) values below 60 mV/dec are found for spin-FETs with Lc≥ 4.05 nm, and the lowest SS value is 39 mV/dec for the spin-FET with Lc=5.75 nm. At room temperature, the values of MR exceed 106%, and the corresponding SS values are below 92 mV/dec with a minimum SS of 82 mV/dec, still demonstrating high performance for designed nanoscale spin-FETs. Our study provides valuable insights into the design of high-performance nanoscale spin-FET devices based on 2D MXenes.