  Quantum dots have the potential to be the brightest deterministic single
photon source with plausible high end applications in quantum computing and
cluster state generation. In this work, we re-examine the design of simple
micropillars by meticulously examining the structural effects of the decay into
leaky channels beyond the atom-like cavity estimation. We show that precise
control of the side losses with the diameter and avoidance of propagating Bloch
modes in the DBR structure can result in easy to manufacture broadband
(Q$\approx750-2500$) micropillars and demonstrate extremely high internal
efficiency ($90.5\%-96.4\%$). We also demonstrate that such cavities naturally
decouple from the phonon sideband, with the phonon sideband reducing by a
factor of $5-33$ allowing us to predict that the photons should show
$99.2\%-99.8\%$ indistinguishability.
