Out of the different
structural phases of molybdenum ditelluride
(MoTe
2
), the distorted octahedral 1T′ possesses
great interest for fundamental physics and is a promising candidate
for the implementation of innovative devices such as topological transistors.
Indeed, 1T′-MoTe
2
is a semimetal with superconductivity,
which has been predicted to be a Weyl semimetal and a quantum spin
Hall insulator in bulk and monolayer form, respectively. Large instability
of monolayer 1T′-MoTe
2
in environmental conditions,
however, has made its investigation extremely challenging so far.
In this work, we demonstrate homogeneous growth of large single-crystal
(up to 500 μm) monolayer 1T′-MoTe
2
via
chemical vapor deposition (CVD) and its stabilization
in air with a scalable encapsulation approach. The encapsulant is
obtained by electrochemically delaminating CVD hexagonal boron nitride
(hBN) from copper foil, and it is applied on the freshly grown 1T′-MoTe
2
via
a top-down dry lamination step. The
structural and electrical properties of encapsulated 1T′-MoTe
2
have been monitored over several months to assess the degree
of degradation of the material. We find that when encapsulated with
hBN, the lifetime of monolayer 1T′-MoTe
2
successfully
increases from a few minutes to more than a month. Furthermore, the
encapsulated monolayer can be subjected to transfer, device processing,
and heating and cooling cycles without degradation of its properties.
The potential of this scalable heterostack is confirmed by the observation
of signatures of low-temperature phase transition in monolayer 1T′-MoTe
2
by both Raman spectroscopy and electrical measurements. The
growth and encapsulation methods reported in this work can be employed
for further fundamental studies of this enticing material as well
as facilitate the technological development of monolayer 1T′-MoTe
2
.