MoS2 single layers were exfoliated on ~7 nm/3 nm Au/Ti or Ag/Ti films deposited on SiO2/Si in our custom-made UHV exfoliation system equipped with in-situ e-beam evaporator, where metal deposition and subsequent exfoliation were performed in the same UHV chamber at the base vacuum ~10 -10 Torr. A detailed description of the system and the exfoliation technique is provided in the methodology section. Videography of the exfoliation process is presented in the Supplementary Videos 1 (touching) and 2 (retraction), which were recorded using a camera fitted to a viewport of the exfoliation system. The in-situ optical images of the exfoliated MoS2 single layers on Au/Ti and Ag/Ti substrates are presented in Figures and), respectively. The microscopic images were captured by an optical microscope attached to the top viewport of the exfoliation system. A discussion of the exfoliation process is provided in the methodology section. The Figures and show the corresponding high-resolution images demonstrating the uniformity of ultra-large single crystalline layers. The dimensions of the exfoliated single layers were determined based on the dimensions of the parent crystal. The photoluminescence (PL) emission from both monolayers is completely quenched, which is related to the common metal-induced quenching of emission.