Strain effect on circularly polarized electroluminescence in transition metal dichalcogenides

Strain effect on circularly polarized electroluminescence (EL) is theoretically analyzed for a p-i-n junction of transition metal dichalcogenides. The electrically controllable circularly polarized EL without the strain effect is understood by valley polarization combined with the electron-hole asymmetry due to the trigonal warping effect in the valence band. The strain enhances circularly polarized EL more efficiently than the trigonal warping effect since the asymmetry occurs in the same direction as the direction of the applied electric field. The calculated result shows that the circular polarization in the strained MoS2 becomes 100% without losing the EL intensity.