  The observation of the electrically tunable and highly confined plasmons in
graphene has stimulated the exploration of interesting properties of plasmons
in other two dimensional materials. Recently, hyperbolic plasmon resonance
modes are observed in exfoliated WTe2 films, a type-II Weyl semimetal with
layered structure, providing a platform for the assembly of plasmons with
hyperbolicity and exotic topological properties. However, the plasmon modes
were observed in relatively thick and small-area films, which restrict the
tunability and application for plasmons. Here, large-area (~ cm) WTe2 films
with different thickness are grown by chemical vapor deposition method, in
which plasmon resonance modes are observed in films with different thickness
down to about 8 nm. Hybridization of plasmon and surface polar phonons of the
substrate is revealed by mapping the plasmon dispersion. The plasmon frequency
is demonstrated to be tunable by changing the temperature and film thickness.
Our results facilitate the development of a tunable and scalable WTe2 plasmonic
system for revealing topological properties and towards various applications in
sensing, imaging and light modulation.
