World's first molecular beam epitaxy (MBE) grown WS2 monolayers. MBE is an epitaxial method for single-crystal quality film deposition which offers high crystallinity and reduced defect density compared to chemical vapor deposition (CVD) or metal-organic chemical vapor deposition (MOCVD) techniques (see HRTEM images below). MBE growth of WS2 monolayers take place in a MBE chamber at a base pressure of 8E-9 Torr and deposition rate is extremely slow (5-100 atoms per second) to reach structural perfection. Typical MBE growth produces monolayer thick WS2 isolated triangles on double-side polished c-cut sapphire. Currently, MBE WS2 is only offered on sapphire substrates but in the near future our MBE substrates will also include mica, graphite, and gold.
Comparison between MBE, CVD, and MOCVD
TEM comparison between MBE, CVD, and MOCVD
Optical images collected from MBE WS2
MBE WS2 suspended on TEM grid
PL spectrum collected from MBE WS2
Raman spectrum collected from MBE WS2