Rational synthesis of bandgap-tunable MS2(1−x)Se2x (M = Mo, W) alloys and their physical properties

Band gap engineering has been opening a way to enhance the performance of two-dimensional (2D) material devices. Here we report a synthesis of ternary MS2(1−x)Se2x (M = Mo, W) alloys with a band gap tunability of ∼170 meV using a solid state reaction method. X-ray photoelectron spectroscopy and Raman scattering characterizations reveal that the change of Se contents can be utilized to tune the composition of the ternary MS2(1−x)Se2x (M = Mo, W) alloys. UV-vis-NIR absorption results conform the realization of tunable band gap in MS2(1−x)Se2x (M = Mo, W) alloys tailored by different Se contents. The electrical transport investigation of the ternary alloys exhibits an n-type semiconductor behavior demonstrated by back-gated field effect transistors.