  Photonic cavities are valued in current research owing to the multitude of
linear and nonlinear effects arising from densely confined light. Cavity
designs consisting of low loss dielectric materials can achieve significant
light confinement, competitive with other schools of cavity design such as
plasmonics. However, the basic concepts in all dielectric photonics such as
anapole resonances in nanodisks have been primarily studied in high index
materials such as WS2 and Si. Without additional measures, low index dielectric
nanodisks struggle to achieve similar levels of light confinement. Here, we
present fabricable design space for higher confinement in a low index
dielectric cavity by incorporating the extensively studied, isolated dielectric
nanodisk into broader host structures. In particular, we focus on hexagonal
boron nitride (hBN), a novel dielectric 2D material with bright, room
temperature single photon emitters and refractive indices of 2.1 and 1.8 in the
inplane and out-of-plane directions. Due to hBN's potential as a quantum light
source, we characterise our cavities by their achievable Purcell factors at the
anapole resonance. The effects of the supporting structures on the cavity
resonances include boosts to the Purcell factor by as much as three-fold to a
maximum observed factor of 6.2.
