Rashba-type spin splitting and transport properties of novel Janus XWGeN2 (X = O, S, Se, Te) monolayers

We discuss and examine the stability, electronic properties, and transport characteristics of asymmetric monolayers XWGeN2 (X = O, S, Se, Te) using ab initio density functional theory. All four monolayers of quintuple-layer atomic Janus XWGeN2 are predicted to be stable and they are all indirect semiconductors in the ground state. When the spin-orbit coupling (SOC) is included, a large spin splitting at the K point is found in XWGeN2 monolayers, particularly, a giant Rashba-type spin splitting is observed around the Gamma point in three structures SWGeN2, SeWGeN2, and TeWGeN2. The Rashba parameters in these structures are directionally isotropic along the high-symmetry directions Gamma-K and Gamma-M and the Rashba constant alpha(R) increases as the X element moves from S to Te. TeWGeN2 has the largest Rashba energy up to 37.4 meV (36.6 meV) in the Gamma-K (Gamma-M) direction. Via the deformation potential method, we calculate the carrier mobility of all four XWGeN2 monolayers. It is found that the electron mobilities of OWGeN2 and SWGeN2 monolayers exceed 200 cm(2) V-1 s(-1), which are suitable for applications in nanoelectronic devices.

Automated summary

In this study, we investigate the stability, electronic properties, and transport characteristics of four asymmetric monolayers XWGeN2 using ab initio density functional theory. The results show that all four monolayers are stable indirect semiconductors, and exhibit significant spin splitting and Rashba-type spin splitting. TeWGeN2 has the largest Rashba energy, which makes it potentially valuable for applications in nanoelectronic devices.