Molecular Beam Epitaxy growth of MoTe$_2$ on Hexagonal Boron Nitride

TL;DR

This paper reports the first successful molecular beam epitaxy growth of MoTe2 on hexagonal boron nitride, revealing phase coexistence and tunable surface properties crucial for 2D material applications.

Contribution

It introduces a novel MBE growth method for MoTe2 on hBN and explores phase control and surface morphology, advancing 2D material synthesis techniques.

Findings

MoTe2 can be grown in multiple crystalline phases on hBN.

Annealing significantly alters the diffusion constant of MoTe2.

Raman spectroscopy indicates coexistence of 2H and 1T' phases.

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, MoSe$_{\tiny{\textrm{2}}}$, MoS$_{\tiny{\textrm{2}}}$ or WSe$_{\tiny{\textrm{2}}}$. Here, we present for the first time the molecular beam epitaxy growth of MoTe$_{\tiny{\textrm{2}}}$ on atomically smooth hexagonal boron nitride (hBN) substrate. Occurrence of MoTe$_{\tiny{\textrm{2}}}$ in various crystalline phases such as distorted octahedral 1T' phase with semimetal properties or hexagonal 2H phase with semiconducting properties opens a possibility of realisation of crystal-phase homostructures with tunable properties. Atomic force microscopy studies of MoTe$_{\tiny{\textrm{2}}}$ grown in a single monolayer regime enable us to determine surface morphology as a function of the growth conditions. The diffusion constant of MoTe$_{\tiny{\textrm{2}}}$ grown on hBN can be altered 5 times by annealing after the growth, reaching about 5 $\cdot$ 10$^{-6}$ cm$^{2}$/s. Raman spectroscopy results suggest a coexistence of both 2H and 1T' MoTe$_{\tiny{\textrm{2}}}$ phases in the studied samples.