Anisotropic Spectroscopy and Electrical Properties of 2D ReS 2(1- x ) Se 2 x Alloys with Distorted 1T Structure.

2D black phosphorus (BP) and rhenium dichalcogenides (ReX2 , X = S, Se) possess intrinsic in-plane anisotropic physical properties arising from their low crystal lattice symmetry, which has inspired their novel applications in electronics, photonics, and optoelectronics. Different from BP with poor environmental stability, ReX2 has low-symmetry distorted 1T structures with excellent stability. In ReX2 , the electronic structure is weakly dependent on layer numbers, which restricts their property tunability and device applications. Here, the properties are tuned, such as optical bandgap, Raman anisotropy, and electrical transport, by alloying 2D ReS2 and ReSe2 . Photoluminescence emission energy of ReS2(1- x ) Se2 x monolayers (x from 0 to 1 with a step of 0.1) can be continuously tuned ranging from 1.62 to 1.31 eV. Polarization behavior of Raman modes, such as ReS2 -like peak at 212 cm-1 , shifts as the composition changes. Anisotropic electrical property is maintained in ReS2(1- x ) Se2 x with high electron mobility along b-axis for all compositions of ReS2(1- x ) Se2 x .