Stacking Order-Dependent Electronic, Optical, and Charge Transport Properties of van der Waals GaS/WXY (X/Y = S, Se, Te) Heterostructures

The introduction of Janus transition-metal dichalcogenide(TMD)monolayers is expected to bring fascinating properties into van derWaals (vdW) heterostructures. Hence, we investigate the electronic,optical, and charge transport properties of GaS/WXY (X/Y = S, Se,Te) vdW heterostructures using first-principles calculations and nonequilibriumGreen's function methods. When the Janus monolayer is flippedupside-down, its stacking order changes from GaS/SWSe to GaS/SeWS,resulting in the reversal of the direction of the out-of-plane dipolemoment. Our results clearly show that the interlayer coupling determinedby the stacking order is negatively correlated with the electron mobilityof the system. Among them, GaS/SWSe and GaS/TeWSe, respectively, possessthe largest and the smallest electron mobility of about 2.1 x10(4) and 3 x 10(2) cm(2)/Vs. We furtherreveal the effect of in-plane strain on the electronic structure ofdifferent stacking orders. At the critical strain, the band alignmenttype is changed and the optical absorption coefficient is enhanced.Our work lays the theoretical foundation for selectively buildingthe stacking order and new means of regulating interface interactionsand provides a new platform for designing high-performance electronicand optoelectronic devices.