Designing High-Performance Nanoscale Spin-MOSFET Devices by Using Two-Dimensional Half-Metallic Cr₂Se₃

Constructing nanoscale spin devices has been a crucial pursuit in the field of nano spintronics. Here, by using the density functional theory (DFT) and nonequilibrium Green's function (NEGF) method, high-performance nanoscale spin-MOSFET devices using half-metallic 2D Cr₂Se₃ as electrodes are theoretically designed. Specifically, seven typical two-dimensional (2D) semiconductors, Sb, Bi, BP, BAs, MoTe₂, WTe₂, and WSeTe (with two different contacting surfaces), are considered here as the channel materials. The properties of contact interfaces between these 2D semiconductors and half-metallic 2D Cr₂Se₃ are first investigated. It is found that except BP and BAs (having Schottky contacts with Cr₂Se₃), the other 2D semiconductors have vertical Ohmic contacts with Cr₂Se₃ among which Cr₂Se₃/Sb, Cr₂Se₃/MoTe₂, Cr₂Se₃/WTe₂, Cr₂Se₃/WSeTe-Se, and Cr₂Se₃/WSeTe-Te retain the half-metallic characteristic. Then, these 2D semiconductors with Ohmic vertical contacts are further used to construct spin-MOSFET devices. The results show that devices constructed by half-metallic vertical contacting systems have nearly 100% SIE and therefore giant MR (>10⁷%) when the gate voltage varies. Furthermore, four designed spin-MOSFET devices, namely, Cr₂Se₃/MoTe₂, Cr₂Se₃/WTe₂, Cr₂Se₃/WSeTe-Se, and Cr₂Se₃/WSeTe-Te spin-MOSFET have high efficient gate modulations on the magnitude of completely spin-polarized source-drain current with Cr₂Se₃/WTe₂ having the smallest SS value of 134.1 mV/dec. The calculations suggest that Cr₂Se₃ is a good candidate for constructing spin-MOSFET devices. Our study sheds light on the design of high-performance nanoscale spin-MOSFET devices by using two-dimensional half-metallic electrodes.