Designing High-Performance\nNanoscale Spin-MOSFET Devices\nby Using Two-Dimensional Half-Metallic Cr<sub>2</sub>Se<sub>3</sub>

Constructing nanoscale spin devices has been a crucial\npursuit\nin the field of nano spintronics. Here, by using the density functional\ntheory (DFT) and nonequilibrium Green’s function (NEGF) method,\nhigh-performance nanoscale spin-MOSFET devices using half-metallic\n2D Cr<sub>2</sub>Se<sub>3</sub> as electrodes are theoretically designed.\nSpecifically, seven typical two-dimensional (2D) semiconductors, Sb,\nBi, BP, BAs, MoTe<sub>2</sub>, WTe<sub>2</sub>, and WSeTe (with two\ndifferent contacting surfaces), are considered here as the channel\nmaterials. The properties of contact interfaces between these 2D semiconductors\nand half-metallic 2D Cr<sub>2</sub>Se<sub>3</sub> are first investigated.\nIt is found that except BP and BAs (having Schottky contacts with\nCr<sub>2</sub>Se<sub>3</sub>), the other 2D semiconductors have vertical\nOhmic contacts with Cr<sub>2</sub>Se<sub>3</sub> among which Cr<sub>2</sub>Se<sub>3</sub>/Sb, Cr<sub>2</sub>Se<sub>3</sub>/MoTe<sub>2</sub>, Cr<sub>2</sub>Se<sub>3</sub>/WTe<sub>2</sub>, Cr<sub>2</sub>Se<sub>3</sub>/WSeTe-Se, and Cr<sub>2</sub>Se<sub>3</sub>/WSeTe-Te retain\nthe half-metallic characteristic. Then, these 2D semiconductors with\nOhmic vertical contacts are further used to construct spin-MOSFET\ndevices. The results show that devices constructed by half-metallic\nvertical contacting systems have nearly 100% SIE and therefore giant\nMR (>10<sup>7</sup>%) when the gate voltage varies. Furthermore,\nfour\ndesigned spin-MOSFET devices, namely, Cr<sub>2</sub>Se<sub>3</sub>/MoTe<sub>2</sub>, Cr<sub>2</sub>Se<sub>3</sub>/WTe<sub>2</sub>,\nCr<sub>2</sub>Se<sub>3</sub>/WSeTe–Se, and Cr<sub>2</sub>Se<sub>3</sub>/WSeTe–Te spin-MOSFET have high efficient gate modulations\non the magnitude of completely spin-polarized source–drain\ncurrent with Cr<sub>2</sub>Se<sub>3</sub>/WTe<sub>2</sub> having the\nsmallest SS value of 134.1 mV/dec. The calculations suggest that Cr<sub>2</sub>Se<sub>3</sub> is a good candidate for constructing spin-MOSFET\ndevices. Our study sheds light on the design of high-performance nanoscale\nspin-MOSFET devices by using two-dimensional half-metallic electrodes.