Laser-assisted conversion from 1T′- MoTe₂to MoTe₂_(1-x)S_2xternary alloys

Two-dimensional (2D) transition metal dichalcogenides (TMds) shows remarkable physical properties and potential for device applications. Most of the semiconducting TMDs are stable in the 2H phase while MoTe₂ is stable in both 2H (semiconducting) and 1T′ (metallic) phases. It makes MoTe₂ an interesting candidate for in-plane interconnects when combined with 2D semiconductors. Here, we report the synthesize of large-area few-layers MoTe₂ using a simple tellurization CVD process. Subsequently, the as-grown transition metal ditelluride was chemically modified using an in situ laser-assisted method in a reactive gas environment. For an optimized set of parameters, the tellurium atoms are replaced by sulfur atoms. The chemical exchange process is monitored in real time via Raman spectroscopy. The site-selective replacement of the chalcogen atoms generate metal-semiconductor heterojunctions. 2D field effect transistors were fabricated to study the electrical response of these lateral heterojunctions. Additionally, we performed first-principle calculations for different chalcogen compositions in the ternary system MoTe_2(1-x)S_2x and found that the band structure evolves with increasing sulfur composition revealing a systematic transition from metal to semiconductor.