Electronic structure and dynamic properties of two-dimensional W x Mo 1? x S 2 ternary alloys from first -principles calculations

Two-dimensional transition metal dichalcogenide materials are of great interest for the development of semiconductor devices because of their diverse properties. In this paper, we discovered the ground states of WxMo1− xS2 alloys and discussed their electronic structures and phonon properties in detail by the cluster expansion method and the first principle calculation. Three ground-state structures of WxMo1− xS2 alloys, W1/3Mo2/3S2, W1/2Mo1/2S2, and W2/3Mo1/3S2, have low order–disorder phase transition temperatures, T1/3 = 102.3 K, T1/2 = 87.8 K, and T2/3 = 102.2 K, estimated by mean field theory. Their bandgaps exhibit a nonlinear increase with increasing W content. All ground structures are dynamically stable without imagine frequency in phonon dispersion. W doping into single layer MoS2 leads low frequency optical modes hybriding with acoustic modes and lowering down the low frequency band due to larger mass of W atoms. All these may improve the developments of WxMo1− xS2 alloys devices. © 2020 Elsevier B.V.