  Although the field of 2D materials has democratized materials science by
making high quality samples accessible cheaply, due to the atomically thin
nature of these systems, an integration with nanostructures is almost always
required to obtain a significant optical response. Traditionally, these
nanostructures are fabricated via electron beam lithography or focused ion beam
milling, which are expensive and large area fabrication can be further time
consuming. In order to overcome this problem, we report the integration of 2D
semiconductors on a cost-effective and large area fabricated nanocone platform.
We show that the plasmon modes of our nanocone structures lead to
photoluminescence (PL) enhancement of monolayer WSe$_2$ by about eight to ten
times compared to the non-plasmonic case, consistent with finite-difference
time-domain simulations. Excitation power-dependent measurements reveal that
our nanocone platform enables a versatile route to engineering the relative
exciton trion contributions to the emission.
