Synthesis of AuCl3 Dopant on MoS2 Devices

The synthesis of AuCl₃ dopant is according to the previous reports^{40 (link)–42 (link)}. Briefly, 30 mg gold chloride (AuCl₃) powders (≥99.99 %, Sigma Aldrich) were dissolved in the 5 ml nitromethane (≥95 %, Sigma Aldrich), then the solutions (20 mM) were sonicated for 3 h at 60 degrees followed by filtration to filter the large Au aggregates. The 20 mM AuCl₃ solutions were then diluted with different concentration (10 mM and 5 mM). Note that all operations were performed in glove box to protect the reagents from the air environment. About 3–5 drops of 5 mM AuCl₃ solutions were dropped on the SiO₂/Si substrate with MoS₂ devices on top and spin-coated at 3000 rpm for 1 min, then baked on the hotplate at 100 °C for 5 min.