  Tungsten ditelluride is a layered transition metal dichalcogenide (TMD) that
has attracted increasing research interest in recent years. WTe2 has
demonstrated large non-saturating magnetoresistance, potential for spintronic
applications and promise as a type-II Weyl semimetal. The majority of works on
WTe2 have relied on mechanically-exfoliated flakes from chemical vapour
transport (CVT) grown crystals for their investigations. While producing
high-quality samples, this method is hindered by several disadvantages
including long synthesis times, high-temperature anneals and an inherent lack
of scalability. In this work, a synthesis method is demonstrated that allows
the production of large-area polycrystalline films of WTe2. This is achieved by
the reaction of pre-deposited films of W and Te at a relatively low temperature
of 550 degC. Sputter X-ray photoelectron spectroscopy reveals the rapid but
self-limiting nature of the oxidation of these WTe2 films in ambient
conditions. The WTe2 films are composed of areas of micrometre sized nanobelts
that can be isolated and offer potential as an alternative to CVT-grown
samples. These nanobelts are highly crystalline with low defect densities
indicated by TEM and show promising initial electrical results.
