  A range of seven different Ag plasmonic arrays formed using nanostructures of
varying shape, size and gap were fabricated using helium-ion lithography (HIL)
on an InGaN/GaN quantum well (QW) substrate. The influence of the array
geometry on plasmon-enhanced F\"orster resonance energy transfer (FRET) from a
single InGaN QW to a ~ 80 nm layer of CdSe/ZnS quantum dots (QDs) embedded in a
poly(methyl methacrylate) (PMMA) matrix is investigated. It is shown that the
energy transfer efficiency is strongly dependent on the array properties and an
efficiency of ~ 51% is observed for a nanoring array. There were no signatures
of FRET in the absence of the arrays. The QD acceptor layer emission is highly
sensitive to the array geometry. A model was developed to confirm that the
increase in the QD emission on the QW substrate compared with a GaN substrate
can be attributed solely to plasmon-enhanced FRET. The individual contributions
of direct enhancement of the QD layer emission by the array and the
plasmon-enhanced FRET are separated out, with the QD emission described by the
product of an array emission factor and an energy transfer factor. It is shown
that while the nanoring geometry results in an energy transfer factor of ~ 1.7
the competing quenching by the array, with an array emission factor of ~ 0.7,
results in only an overall gain of ~ 14% in the QD emission. The QD emission
was enhanced by ~ 71% for a nanobox array, resulting from the combination of a
more modest energy transfer factor of 1.2 coupled with an array emission factor
of ~ 1.4.
