Molecular beam epitaxy growth of MoTe2 on hexagonal boron nitride

Abstract

Hexagonal boron nitride has already been proven to serve as a decent substrate for high quality epitaxial growth of several 2D materials, such as graphene, MoSe2, MoS2 or WSe2. Here, we present for the first time the molecular beam epitaxy growth of MoTe2 on atomically smooth hexagonal boron nitride (hBN) substrate. Occurrence of MoTe2 in various crystalline phases such as distorted octahedral 1T’ phase with semimetal properties or hexagonal 2H phase with semiconducting properties opens a possibility of realization of crystal-phase homostructures with tunable properties. Atomic force microscopy studies of MoTe2 grown in a single monolayer regime enable us to observe impact of growth conditions on formation of various structures: flat grains, net of one-dimensional structures, quasi continuous monolayers with bilayer contribution. Comparison of the distribution of the thickness with Poisson distribution shows that tested growth conditions favorite formation of grains with monolayer thickness. The diffusion constant of MoTe2 grown on hBN can reach order of 10−6 cm2/s for typical growth conditions. Raman spectroscopy results suggest a coexistence of various phases with domination of 2H MoTe2 for samples grown at lower temperatures. XPS measurements confirm the stoichiometry of MoTe2.