Substrate temperature dependence of the crystalline quality for the synthesis of pure-phase MoTe2 on graphene/6H-SiC(0001) by molecular beam epitaxy

MoTe2 has two stable solid phases. 2H-MoTe2 is semiconducting while 1T' is semimetallic. The selective synthesis of pure-phase thin films is still challenging. In this study, we have investigated the growth temperature dependence of MoTe2 synthesized by molecular beam epitaxy and have identified the optimum temperature for growing the stoichiometric films. It is confirmed that the crystalline quality of MoTe2 strongly depends on the substrate temperature. Post-growth annealing of grown layers at 400 degrees C stabilizes the semiconducting phase. The structural properties and the phase change in our materials are analyzed in details by reflection high energy electron diffraction, low energy electron diffraction, auger electron spectroscopy, x-ray photoemission spectroscopy, and scanning tunneling microscopy.