Growth and Characterization of TMDs (MoS$_{\mathrm{2}}$, MoSe$_{\mathrm{2}}$, WS$_{\mathrm{2}}$, WSe$_{\mathrm{2}}$ {\&} MoTe$_{\mathrm{2}})$ and Their Alloys on Various Substrates

Transition Metal Dichalcogenides (TMDs) have been of interest over the past years due to their exciting semiconducting properties. In the bulk, TMDs possess a native indirect bandgap and transition to a direct bandgap as they approach the monolayer limit. The bandgaps range from 1.15 eV to 1.95 eV depending on composition. Using organic liquids and/or inorganic powders as precursors, CVD growth has been realized for MX$_{\mathrm{2}}$ TMDs (M $=$ Mo, W; X $=$ S, Se) and their alloys at tunable compositions. I will present the effect of tuning parameters such as temperature, gas flow, time of heat and hold on the resultant single-layer films. Different precursors can lead to different overall film structures and enable different growth conditions. The films can either be made homogeneous in bandgap or gradients of material/bandgap can be grown. The use of different substrates (dielectric, ferroelectric, piezoelectric, semicoundcing , insulating, patterned) allows an additional degree of freedom and sets the stage for subsequent experiments. I will talk about preparation methods tailored toward direct applicability of surface acoustic spectroscopy, scanning photocurrent microscopy, and ferroelectric gating of the single-layer films.